getCanonicalPackages returns packages with same name in different versions

src/Composer/Repository/ArrayRepository.php

@@ -26,6 +26,7 @@ use Composer\Package\LinkConstraint\VersionConstraint;
  */
 class ArrayRepository implements RepositoryInterface
 {
+    /** @var PackageInterface[] */
     protected $packages;
 
     public function __construct(array $packages = array())

src/Composer/Repository/WritableArrayRepository.php

@@ -42,11 +42,12 @@ class WritableArrayRepository extends ArrayRepository implements WritableReposit
     {
         $packages = $this->getPackages();
 
-        // get at most one package of each name, prefering non-aliased ones
+        // get at most one package of each (name, version) combination, prefering non-aliased ones
         $packagesByName = array();
         foreach ($packages as $package) {
-            if (!isset($packagesByName[$package->getName()]) || $packagesByName[$package->getName()] instanceof AliasPackage) {
+            $index = $package->getName() . $package->getVersion();
-                $packagesByName[$package->getName()] = $package;
+            if (!isset($packagesByName[$index]) || $packagesByName[$index] instanceof AliasPackage) {
+                $packagesByName[$index] = $package;
             }
         }
 

tests/Composer/Test/Repository/WritableArrayRepositoryTest.php

@@ -0,0 +1,29 @@
+<?php
+
+/*
+ * This file is part of Composer.
+ *
+ * (c) Nils Adermann <naderman@naderman.de>
+ *     Jordi Boggiano <j.boggiano@seld.be>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Composer\Test\Repository;
+
+use Composer\Repository\WritableArrayRepository;
+use Composer\TestCase;
+
+final class WritableArrayRepositoryTest extends TestCase
+{
+    public function testGetCanonicalPackagesReturnsDifferentVersionsOfSameNamedPackage()
+    {
+        $repository = new WritableArrayRepository();
+
+        $repository->addPackage($this->getPackage('foo', 1));
+        $repository->addPackage($this->getPackage('foo', 2));
+
+        $this->assertCount(2, $repository->getCanonicalPackages());
+    }
+}