diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0d1d68b..0035e26 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,6 @@
 # `1.0.0` (unreleased)
 
+* Avoid duplicating edges when there is multiple extended services
 * Display extended services as components with inverted arrows
 * Display services as components
 * Display volumes as folders
diff --git a/composer.lock b/composer.lock
index a538a6b..70160e5 100644
--- a/composer.lock
+++ b/composer.lock
@@ -145,37 +145,87 @@
             "time": "2015-03-08 10:30:28"
         },
         {
-            "name": "symfony/console",
-            "version": "v3.1.3",
+            "name": "psr/log",
+            "version": "1.0.2",
             "source": {
                 "type": "git",
-                "url": "https://github.com/symfony/console.git",
-                "reference": "f9e638e8149e9e41b570ff092f8007c477ef0ce5"
+                "url": "https://github.com/php-fig/log.git",
+                "reference": "4ebe3a8bf773a19edfe0a84b6585ba3d401b724d"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/console/zipball/f9e638e8149e9e41b570ff092f8007c477ef0ce5",
-                "reference": "f9e638e8149e9e41b570ff092f8007c477ef0ce5",
+                "url": "https://api.github.com/repos/php-fig/log/zipball/4ebe3a8bf773a19edfe0a84b6585ba3d401b724d",
+                "reference": "4ebe3a8bf773a19edfe0a84b6585ba3d401b724d",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=5.3.0"
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "1.0.x-dev"
+                }
+            },
+            "autoload": {
+                "psr-4": {
+                    "Psr\\Log\\": "Psr/Log/"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "PHP-FIG",
+                    "homepage": "http://www.php-fig.org/"
+                }
+            ],
+            "description": "Common interface for logging libraries",
+            "homepage": "https://github.com/php-fig/log",
+            "keywords": [
+                "log",
+                "psr",
+                "psr-3"
+            ],
+            "time": "2016-10-10 12:19:37"
+        },
+        {
+            "name": "symfony/console",
+            "version": "v3.2.1",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/symfony/console.git",
+                "reference": "d12aa9ca20f4db83ec58410978dab6afcb9d6aaa"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/symfony/console/zipball/d12aa9ca20f4db83ec58410978dab6afcb9d6aaa",
+                "reference": "d12aa9ca20f4db83ec58410978dab6afcb9d6aaa",
                 "shasum": ""
             },
             "require": {
                 "php": ">=5.5.9",
+                "symfony/debug": "~2.8|~3.0",
                 "symfony/polyfill-mbstring": "~1.0"
             },
             "require-dev": {
                 "psr/log": "~1.0",
                 "symfony/event-dispatcher": "~2.8|~3.0",
+                "symfony/filesystem": "~2.8|~3.0",
                 "symfony/process": "~2.8|~3.0"
             },
             "suggest": {
                 "psr/log": "For using the console logger",
                 "symfony/event-dispatcher": "",
+                "symfony/filesystem": "",
                 "symfony/process": ""
             },
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "3.1-dev"
+                    "dev-master": "3.2-dev"
                 }
             },
             "autoload": {
@@ -202,20 +252,77 @@
             ],
             "description": "Symfony Console Component",
             "homepage": "https://symfony.com",
-            "time": "2016-07-26 08:04:17"
+            "time": "2016-12-11 14:34:22"
         },
         {
-            "name": "symfony/polyfill-mbstring",
-            "version": "v1.2.0",
+            "name": "symfony/debug",
+            "version": "v3.2.1",
             "source": {
                 "type": "git",
-                "url": "https://github.com/symfony/polyfill-mbstring.git",
-                "reference": "dff51f72b0706335131b00a7f49606168c582594"
+                "url": "https://github.com/symfony/debug.git",
+                "reference": "9f923e68d524a3095c5a2ae5fc7220c7cbc12231"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/polyfill-mbstring/zipball/dff51f72b0706335131b00a7f49606168c582594",
-                "reference": "dff51f72b0706335131b00a7f49606168c582594",
+                "url": "https://api.github.com/repos/symfony/debug/zipball/9f923e68d524a3095c5a2ae5fc7220c7cbc12231",
+                "reference": "9f923e68d524a3095c5a2ae5fc7220c7cbc12231",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=5.5.9",
+                "psr/log": "~1.0"
+            },
+            "conflict": {
+                "symfony/http-kernel": ">=2.3,<2.3.24|~2.4.0|>=2.5,<2.5.9|>=2.6,<2.6.2"
+            },
+            "require-dev": {
+                "symfony/class-loader": "~2.8|~3.0",
+                "symfony/http-kernel": "~2.8|~3.0"
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "3.2-dev"
+                }
+            },
+            "autoload": {
+                "psr-4": {
+                    "Symfony\\Component\\Debug\\": ""
+                },
+                "exclude-from-classmap": [
+                    "/Tests/"
+                ]
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Fabien Potencier",
+                    "email": "fabien@symfony.com"
+                },
+                {
+                    "name": "Symfony Community",
+                    "homepage": "https://symfony.com/contributors"
+                }
+            ],
+            "description": "Symfony Debug Component",
+            "homepage": "https://symfony.com",
+            "time": "2016-11-16 22:18:16"
+        },
+        {
+            "name": "symfony/polyfill-mbstring",
+            "version": "v1.3.0",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/symfony/polyfill-mbstring.git",
+                "reference": "e79d363049d1c2128f133a2667e4f4190904f7f4"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/symfony/polyfill-mbstring/zipball/e79d363049d1c2128f133a2667e4f4190904f7f4",
+                "reference": "e79d363049d1c2128f133a2667e4f4190904f7f4",
                 "shasum": ""
             },
             "require": {
@@ -227,7 +334,7 @@
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "1.2-dev"
+                    "dev-master": "1.3-dev"
                 }
             },
             "autoload": {
@@ -261,29 +368,35 @@
                 "portable",
                 "shim"
             ],
-            "time": "2016-05-18 14:26:46"
+            "time": "2016-11-14 01:06:16"
         },
         {
             "name": "symfony/yaml",
-            "version": "v3.1.3",
+            "version": "v3.2.1",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/yaml.git",
-                "reference": "1819adf2066880c7967df7180f4f662b6f0567ac"
+                "reference": "a7095af4b97a0955f85c8989106c249fa649011f"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/yaml/zipball/1819adf2066880c7967df7180f4f662b6f0567ac",
-                "reference": "1819adf2066880c7967df7180f4f662b6f0567ac",
+                "url": "https://api.github.com/repos/symfony/yaml/zipball/a7095af4b97a0955f85c8989106c249fa649011f",
+                "reference": "a7095af4b97a0955f85c8989106c249fa649011f",
                 "shasum": ""
             },
             "require": {
                 "php": ">=5.5.9"
             },
+            "require-dev": {
+                "symfony/console": "~2.8|~3.0"
+            },
+            "suggest": {
+                "symfony/console": "For validating YAML files using the lint command"
+            },
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "3.1-dev"
+                    "dev-master": "3.2-dev"
                 }
             },
             "autoload": {
@@ -310,22 +423,22 @@
             ],
             "description": "Symfony Yaml Component",
             "homepage": "https://symfony.com",
-            "time": "2016-07-17 14:02:08"
+            "time": "2016-12-10 10:07:06"
         }
     ],
     "packages-dev": [
         {
             "name": "crysalead/kahlan",
-            "version": "2.5.4",
+            "version": "2.5.6",
             "source": {
                 "type": "git",
                 "url": "https://github.com/crysalead/kahlan.git",
-                "reference": "0f5deb7faa3a7a324bf0dc0186190ea18bc1eff3"
+                "reference": "64e48c213ee3af4d7d6fe1c13d907f77f11ca5d4"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/crysalead/kahlan/zipball/0f5deb7faa3a7a324bf0dc0186190ea18bc1eff3",
-                "reference": "0f5deb7faa3a7a324bf0dc0186190ea18bc1eff3",
+                "url": "https://api.github.com/repos/crysalead/kahlan/zipball/64e48c213ee3af4d7d6fe1c13d907f77f11ca5d4",
+                "reference": "64e48c213ee3af4d7d6fe1c13d907f77f11ca5d4",
                 "shasum": ""
             },
             "require": {
@@ -363,39 +476,40 @@
                 "testing",
                 "unit test"
             ],
-            "time": "2016-06-15 15:07:49"
+            "abandoned": "kahlan/kahlan",
+            "time": "2016-08-18 13:29:17"
         },
         {
             "name": "friendsofphp/php-cs-fixer",
-            "version": "v1.11.6",
+            "version": "v1.13.1",
             "source": {
                 "type": "git",
                 "url": "https://github.com/FriendsOfPHP/PHP-CS-Fixer.git",
-                "reference": "41dc93abd2937a85a3889e28765231d574d2bac8"
+                "reference": "0ea4f7ed06ca55da1d8fc45da26ff87f261c4088"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/FriendsOfPHP/PHP-CS-Fixer/zipball/41dc93abd2937a85a3889e28765231d574d2bac8",
-                "reference": "41dc93abd2937a85a3889e28765231d574d2bac8",
+                "url": "https://api.github.com/repos/FriendsOfPHP/PHP-CS-Fixer/zipball/0ea4f7ed06ca55da1d8fc45da26ff87f261c4088",
+                "reference": "0ea4f7ed06ca55da1d8fc45da26ff87f261c4088",
                 "shasum": ""
             },
             "require": {
                 "ext-tokenizer": "*",
-                "php": ">=5.3.6",
-                "sebastian/diff": "~1.1",
-                "symfony/console": "~2.3|~3.0",
-                "symfony/event-dispatcher": "~2.1|~3.0",
-                "symfony/filesystem": "~2.1|~3.0",
-                "symfony/finder": "~2.1|~3.0",
-                "symfony/process": "~2.3|~3.0",
-                "symfony/stopwatch": "~2.5|~3.0"
+                "php": "^5.3.6 || >=7.0 <7.2",
+                "sebastian/diff": "^1.1",
+                "symfony/console": "^2.3 || ^3.0",
+                "symfony/event-dispatcher": "^2.1 || ^3.0",
+                "symfony/filesystem": "^2.1 || ^3.0",
+                "symfony/finder": "^2.1 || ^3.0",
+                "symfony/process": "^2.3 || ^3.0",
+                "symfony/stopwatch": "^2.5 || ^3.0"
             },
             "conflict": {
                 "hhvm": "<3.9"
             },
             "require-dev": {
                 "phpunit/phpunit": "^4.5|^5",
-                "satooshi/php-coveralls": "^0.7.1"
+                "satooshi/php-coveralls": "^1.0"
             },
             "bin": [
                 "php-cs-fixer"
@@ -421,7 +535,7 @@
                 }
             ],
             "description": "A tool to automatically fix PHP code style",
-            "time": "2016-07-22 06:46:28"
+            "time": "2016-12-01 00:05:05"
         },
         {
             "name": "sebastian/diff",
@@ -477,16 +591,16 @@
         },
         {
             "name": "symfony/event-dispatcher",
-            "version": "v3.1.3",
+            "version": "v3.2.1",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/event-dispatcher.git",
-                "reference": "c0c00c80b3a69132c4e55c3e7db32b4a387615e5"
+                "reference": "e8f47a327c2f0fd5aa04fa60af2b693006ed7283"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/event-dispatcher/zipball/c0c00c80b3a69132c4e55c3e7db32b4a387615e5",
-                "reference": "c0c00c80b3a69132c4e55c3e7db32b4a387615e5",
+                "url": "https://api.github.com/repos/symfony/event-dispatcher/zipball/e8f47a327c2f0fd5aa04fa60af2b693006ed7283",
+                "reference": "e8f47a327c2f0fd5aa04fa60af2b693006ed7283",
                 "shasum": ""
             },
             "require": {
@@ -506,7 +620,7 @@
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "3.1-dev"
+                    "dev-master": "3.2-dev"
                 }
             },
             "autoload": {
@@ -533,20 +647,20 @@
             ],
             "description": "Symfony EventDispatcher Component",
             "homepage": "https://symfony.com",
-            "time": "2016-07-19 10:45:57"
+            "time": "2016-10-13 06:29:04"
         },
         {
             "name": "symfony/filesystem",
-            "version": "v3.1.3",
+            "version": "v3.2.1",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/filesystem.git",
-                "reference": "bb29adceb552d202b6416ede373529338136e84f"
+                "reference": "8d4cf7561a5b17e5eb7a02b80d0b8f014a3796d4"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/filesystem/zipball/bb29adceb552d202b6416ede373529338136e84f",
-                "reference": "bb29adceb552d202b6416ede373529338136e84f",
+                "url": "https://api.github.com/repos/symfony/filesystem/zipball/8d4cf7561a5b17e5eb7a02b80d0b8f014a3796d4",
+                "reference": "8d4cf7561a5b17e5eb7a02b80d0b8f014a3796d4",
                 "shasum": ""
             },
             "require": {
@@ -555,7 +669,7 @@
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "3.1-dev"
+                    "dev-master": "3.2-dev"
                 }
             },
             "autoload": {
@@ -582,20 +696,20 @@
             ],
             "description": "Symfony Filesystem Component",
             "homepage": "https://symfony.com",
-            "time": "2016-07-20 05:44:26"
+            "time": "2016-11-24 00:46:43"
         },
         {
             "name": "symfony/finder",
-            "version": "v3.1.3",
+            "version": "v3.2.1",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/finder.git",
-                "reference": "8201978de88a9fa0923e18601bb17f1df9c721e7"
+                "reference": "a69cb5d455b4885ca376dc5bb3e1155cc8c08c4b"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/finder/zipball/8201978de88a9fa0923e18601bb17f1df9c721e7",
-                "reference": "8201978de88a9fa0923e18601bb17f1df9c721e7",
+                "url": "https://api.github.com/repos/symfony/finder/zipball/a69cb5d455b4885ca376dc5bb3e1155cc8c08c4b",
+                "reference": "a69cb5d455b4885ca376dc5bb3e1155cc8c08c4b",
                 "shasum": ""
             },
             "require": {
@@ -604,7 +718,7 @@
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "3.1-dev"
+                    "dev-master": "3.2-dev"
                 }
             },
             "autoload": {
@@ -631,20 +745,20 @@
             ],
             "description": "Symfony Finder Component",
             "homepage": "https://symfony.com",
-            "time": "2016-06-29 05:41:56"
+            "time": "2016-12-13 09:39:43"
         },
         {
             "name": "symfony/process",
-            "version": "v3.1.3",
+            "version": "v3.2.1",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/process.git",
-                "reference": "04c2dfaae4ec56a5c677b0c69fac34637d815758"
+                "reference": "02ea84847aad71be7e32056408bb19f3a616cdd3"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/process/zipball/04c2dfaae4ec56a5c677b0c69fac34637d815758",
-                "reference": "04c2dfaae4ec56a5c677b0c69fac34637d815758",
+                "url": "https://api.github.com/repos/symfony/process/zipball/02ea84847aad71be7e32056408bb19f3a616cdd3",
+                "reference": "02ea84847aad71be7e32056408bb19f3a616cdd3",
                 "shasum": ""
             },
             "require": {
@@ -653,7 +767,7 @@
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "3.1-dev"
+                    "dev-master": "3.2-dev"
                 }
             },
             "autoload": {
@@ -680,20 +794,20 @@
             ],
             "description": "Symfony Process Component",
             "homepage": "https://symfony.com",
-            "time": "2016-07-28 11:13:48"
+            "time": "2016-11-24 10:40:28"
         },
         {
             "name": "symfony/stopwatch",
-            "version": "v3.1.3",
+            "version": "v3.2.1",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/stopwatch.git",
-                "reference": "bb42806b12c5f89db4ebf64af6741afe6d8457e1"
+                "reference": "5b139e1c4290e6c7640ba80d9c9b5e49ef22b841"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/stopwatch/zipball/bb42806b12c5f89db4ebf64af6741afe6d8457e1",
-                "reference": "bb42806b12c5f89db4ebf64af6741afe6d8457e1",
+                "url": "https://api.github.com/repos/symfony/stopwatch/zipball/5b139e1c4290e6c7640ba80d9c9b5e49ef22b841",
+                "reference": "5b139e1c4290e6c7640ba80d9c9b5e49ef22b841",
                 "shasum": ""
             },
             "require": {
@@ -702,7 +816,7 @@
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "3.1-dev"
+                    "dev-master": "3.2-dev"
                 }
             },
             "autoload": {
@@ -729,7 +843,7 @@
             ],
             "description": "Symfony Stopwatch Component",
             "homepage": "https://symfony.com",
-            "time": "2016-06-29 05:41:56"
+            "time": "2016-06-29 05:43:10"
         }
     ],
     "aliases": [],
diff --git a/src/functions.php b/src/functions.php
index e4f32fa..9b27ce7 100644
--- a/src/functions.php
+++ b/src/functions.php
@@ -409,7 +409,22 @@ function addNetwork(Graph $graph, string $name, string $type = null)
  */
 function addRelation(Vertex $from, Vertex $to, string $type, string $alias = null, bool $bidirectional = false) : Edge\Directed
 {
-    $edge = $from->createEdgeTo($to);
+    $edge = null;
+
+    if ($from->hasEdgeTo($to)) {
+        $edges = $from->getEdgesTo($to);
+
+        foreach ($edges as $edge) {
+            if ($edge->getAttribute('docker_compose.type') === $type) {
+                break;
+            }
+        }
+    }
+
+    if (null === $edge) {
+        $edge = $from->createEdgeTo($to);
+    }
+
     $edge->setAttribute('docker_compose.type', $type);
 
     if ($alias !== null) {