diff --git a/CHANGELOG b/CHANGELOG
index 97ad620ae15..87d05f1797b 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,5 +1,6 @@
 * 1.27.0 (2016-XX-XX)
 
+ * fixed regression when registering two extensions having the same class name
  * deprecated Twig_LoaderInterface::getSource() (implement Twig_SourceContextLoaderInterface instead)
  * fixed the filesystem loader with relative paths
  * deprecated Twig_Node::getLine() in favor of Twig_Node::getTemplateLine()
diff --git a/lib/Twig/Environment.php b/lib/Twig/Environment.php
index edc60e91756..fd2660f67b6 100644
--- a/lib/Twig/Environment.php
+++ b/lib/Twig/Environment.php
@@ -49,7 +49,7 @@ class Twig_Environment
     private $bcWriteCacheFile = false;
     private $bcGetCacheFilename = false;
     private $lastModifiedExtension = 0;
-    private $legacyExtensionNames = array();
+    private $extensionsByClass = array();
     private $runtimeLoaders = array();
     private $runtimes = array();
     private $optionsHash;
@@ -816,12 +816,16 @@ public function initRuntime()
      */
     public function hasExtension($class)
     {
-        if (isset($this->legacyExtensionNames[$class])) {
-            $class = $this->legacyExtensionNames[$class];
-            @trigger_error(sprintf('Referencing the "%s" extension by its name (defined by getName()) is deprecated since 1.26 and will be removed in Twig 2.0. Use the Fully Qualified Extension Class Name instead.', $class), E_USER_DEPRECATED);
+        $class = ltrim($class, '\\');
+        if (isset($this->extensions[$class])) {
+            if ($class !== get_class($this->extensions[$class])) {
+                @trigger_error(sprintf('Referencing the "%s" extension by its name (defined by getName()) is deprecated since 1.26 and will be removed in Twig 2.0. Use the Fully Qualified Extension Class Name instead.', $class), E_USER_DEPRECATED);
+            }
+
+            return true;
         }
 
-        return isset($this->extensions[ltrim($class, '\\')]);
+        return isset($this->extensionsByClass[ltrim($class, '\\')]);
     }
 
     /**
@@ -841,18 +845,21 @@ public function addRuntimeLoader(Twig_RuntimeLoaderInterface $loader)
      */
     public function getExtension($class)
     {
-        if (isset($this->legacyExtensionNames[$class])) {
-            $class = $this->legacyExtensionNames[$class];
-            @trigger_error(sprintf('Referencing the "%s" extension by its name (defined by getName()) is deprecated since 1.26 and will be removed in Twig 2.0. Use the Fully Qualified Extension Class Name instead.', $class), E_USER_DEPRECATED);
-        }
-
         $class = ltrim($class, '\\');
 
-        if (!isset($this->extensions[$class])) {
+        if (isset($this->extensions[$class])) {
+            if ($class !== get_class($this->extensions[$class])) {
+                @trigger_error(sprintf('Referencing the "%s" extension by its name (defined by getName()) is deprecated since 1.26 and will be removed in Twig 2.0. Use the Fully Qualified Extension Class Name instead.', $class), E_USER_DEPRECATED);
+            }
+
+            return $this->extensions[$class];
+        }
+
+        if (!isset($this->extensionsByClass[$class])) {
             throw new Twig_Error_Runtime(sprintf('The "%s" extension is not enabled.', $class));
         }
 
-        return $this->extensions[$class];
+        return $this->extensionsByClass[$class];
     }
 
     /**
@@ -886,25 +893,21 @@ public function getRuntime($class)
      */
     public function addExtension(Twig_ExtensionInterface $extension)
     {
-        $class = get_class($extension);
-
         if ($this->extensionInitialized) {
-            throw new LogicException(sprintf('Unable to register extension "%s" as extensions have already been initialized.', $class));
+            throw new LogicException(sprintf('Unable to register extension "%s" as extensions have already been initialized.', $extension->getName()));
         }
 
-        $m = new ReflectionMethod($extension, 'getName');
-        $legacyName = 'Twig_Extension' !== $m->getDeclaringClass()->getName() ? $extension->getName() : null;
-
-        if (isset($this->extensions[$class]) || (null !== $legacyName && isset($this->legacyExtensionNames[$legacyName]))) {
-            unset($this->extensions[$this->legacyExtensionNames[$legacyName]], $this->legacyExtensionNames[$legacyName]);
-            @trigger_error(sprintf('The possibility to register the same extension twice ("%s") is deprecated since version 1.23 and will be removed in Twig 2.0. Use proper PHP inheritance instead.', $class), E_USER_DEPRECATED);
+        $class = get_class($extension);
+        if ($class !== $extension->getName()) {
+            if (isset($this->extensions[$extension->getName()])) {
+                unset($this->extensions[$extension->getName()], $this->extensionsByClass[$class]);
+                @trigger_error(sprintf('The possibility to register the same extension twice ("%s") is deprecated since version 1.23 and will be removed in Twig 2.0. Use proper PHP inheritance instead.', $extension->getName()), E_USER_DEPRECATED);
+            }
         }
 
         $this->lastModifiedExtension = 0;
-        if ($legacyName !== $class) {
-            $this->legacyExtensionNames[$legacyName] = $class;
-        }
-        $this->extensions[$class] = $extension;
+        $this->extensionsByClass[$class] = $extension;
+        $this->extensions[$extension->getName()] = $extension;
         $this->updateOptionsHash();
     }
 
@@ -921,16 +924,20 @@ public function removeExtension($name)
     {
         @trigger_error(sprintf('The %s method is deprecated since version 1.12 and will be removed in Twig 2.0.', __METHOD__), E_USER_DEPRECATED);
 
-        if (isset($this->legacyExtensionNames[$name])) {
-            $name = $this->legacyExtensionNames[$name];
-            @trigger_error(sprintf('Referencing the "%s" extension by its name (defined by getName()) is deprecated since 1.26 and will be removed in Twig 2.0. Use the Fully Qualified Extension Class Name instead.', $name), E_USER_DEPRECATED);
-        }
-
         if ($this->extensionInitialized) {
             throw new LogicException(sprintf('Unable to remove extension "%s" as extensions have already been initialized.', $name));
         }
 
-        unset($this->extensions[ltrim($name, '\\')]);
+        $class = ltrim($name, '\\');
+        if (isset($this->extensions[$class])) {
+            if ($class !== get_class($this->extensions[$class])) {
+                @trigger_error(sprintf('Referencing the "%s" extension by its name (defined by getName()) is deprecated since 1.26 and will be removed in Twig 2.0. Use the Fully Qualified Extension Class Name instead.', $class), E_USER_DEPRECATED);
+            }
+
+            unset($this->extensions[$class]);
+        }
+
+        unset($this->extensions[$class]);
         $this->updateOptionsHash();
     }
 
diff --git a/test/Twig/Tests/EnvironmentTest.php b/test/Twig/Tests/EnvironmentTest.php
index 0eba7307cdc..340ec453b47 100644
--- a/test/Twig/Tests/EnvironmentTest.php
+++ b/test/Twig/Tests/EnvironmentTest.php
@@ -277,6 +277,27 @@ public function testAutoReloadOutdatedCacheHit()
         $twig->loadTemplate($templateName);
     }
 
+    /**
+     * @group legacy
+     */
+    public function testHasGetExtensionWithDynamicName()
+    {
+        $twig = new Twig_Environment($this->getMockBuilder('Twig_LoaderInterface')->getMock());
+
+        $ext1 = new Twig_Tests_EnvironmentTest_Extension_DynamicWithDeprecatedName('ext1');
+        $ext2 = new Twig_Tests_EnvironmentTest_Extension_DynamicWithDeprecatedName('ext2');
+        $twig->addExtension($ext1);
+        $twig->addExtension($ext2);
+
+        $this->assertTrue($twig->hasExtension('ext1'));
+        $this->assertTrue($twig->hasExtension('ext2'));
+
+        $this->assertTrue($twig->hasExtension('Twig_Tests_EnvironmentTest_Extension_DynamicWithDeprecatedName'));
+
+        $this->assertSame($ext1, $twig->getExtension('ext1'));
+        $this->assertSame($ext2, $twig->getExtension('ext2'));
+    }
+
     public function testHasGetExtensionByClassName()
     {
         $twig = new Twig_Environment($this->getMockBuilder('Twig_LoaderInterface')->getMock());
@@ -538,6 +559,21 @@ public function getName()
     }
 }
 
+class Twig_Tests_EnvironmentTest_Extension_DynamicWithDeprecatedName extends Twig_Extension
+{
+    private $name;
+
+    public function __construct($name)
+    {
+        $this->name = $name;
+    }
+
+    public function getName()
+    {
+        return $this->name;
+    }
+}
+
 class Twig_Tests_EnvironmentTest_TokenParser extends Twig_TokenParser
 {
     public function parse(Twig_Token $token)