diff --git a/src/Symfony/Component/Form/Extension/DataCollector/FormDataCollector.php b/src/Symfony/Component/Form/Extension/DataCollector/FormDataCollector.php
index b72a5739f843d..d3f5da7894ce7 100644
--- a/src/Symfony/Component/Form/Extension/DataCollector/FormDataCollector.php
+++ b/src/Symfony/Component/Form/Extension/DataCollector/FormDataCollector.php
@@ -256,7 +256,7 @@ public function serialize()
                     case 'resolved_options':
                     case 'default_data':
                     case 'submitted_data':
-                        if ($v) {
+                        if (is_array($v)) {
                             $form[$k] = array_map($cloneVar, $v);
                         }
                         break;
diff --git a/src/Symfony/Component/Form/Tests/Extension/DataCollector/FormDataCollectorTest.php b/src/Symfony/Component/Form/Tests/Extension/DataCollector/FormDataCollectorTest.php
index 0fddf14dc57bc..83c3d1d94d49a 100644
--- a/src/Symfony/Component/Form/Tests/Extension/DataCollector/FormDataCollectorTest.php
+++ b/src/Symfony/Component/Form/Tests/Extension/DataCollector/FormDataCollectorTest.php
@@ -342,6 +342,114 @@ public function testBuildFinalFormTree()
         ), $this->dataCollector->getData());
     }
 
+    public function testSerializeWithFormAddedMultipleTimes()
+    {
+        $form1 = $this->createForm('form1');
+        $form2 = $this->createForm('form2');
+        $child1 = $this->createForm('child1');
+
+        $form1View = new FormView();
+        $form2View = new FormView();
+        $child1View = new FormView();
+        $child1View->vars['is_selected'] = function ($choice, array $values) {
+            return in_array($choice, $values, true);
+        };
+
+        $form1->add($child1);
+        $form2->add($child1);
+
+        $form1View->children['child1'] = $child1View;
+        $form2View->children['child1'] = $child1View;
+
+        $this->dataExtractor->expects($this->at(0))
+            ->method('extractConfiguration')
+            ->with($form1)
+            ->will($this->returnValue(array('config' => 'foo')));
+        $this->dataExtractor->expects($this->at(1))
+            ->method('extractConfiguration')
+            ->with($child1)
+            ->will($this->returnValue(array('config' => 'bar')));
+
+        $this->dataExtractor->expects($this->at(2))
+            ->method('extractDefaultData')
+            ->with($form1)
+            ->will($this->returnValue(array('default_data' => 'foo')));
+        $this->dataExtractor->expects($this->at(3))
+            ->method('extractDefaultData')
+            ->with($child1)
+            ->will($this->returnValue(array('default_data' => 'bar')));
+
+        $this->dataExtractor->expects($this->at(4))
+            ->method('extractSubmittedData')
+            ->with($form1)
+            ->will($this->returnValue(array('submitted_data' => 'foo')));
+        $this->dataExtractor->expects($this->at(5))
+            ->method('extractSubmittedData')
+            ->with($child1)
+            ->will($this->returnValue(array('submitted_data' => 'bar')));
+
+        $this->dataExtractor->expects($this->at(6))
+            ->method('extractViewVariables')
+            ->with($form1View)
+            ->will($this->returnValue(array('view_vars' => 'foo')));
+
+        $this->dataExtractor->expects($this->at(7))
+            ->method('extractViewVariables')
+            ->with($child1View)
+            ->will($this->returnValue(array('view_vars' => $child1View->vars)));
+        
+        $this->dataExtractor->expects($this->at(8))
+            ->method('extractConfiguration')
+            ->with($form2)
+            ->will($this->returnValue(array('config' => 'foo')));
+        $this->dataExtractor->expects($this->at(9))
+            ->method('extractConfiguration')
+            ->with($child1)
+            ->will($this->returnValue(array('config' => 'bar')));
+
+        $this->dataExtractor->expects($this->at(10))
+            ->method('extractDefaultData')
+            ->with($form2)
+            ->will($this->returnValue(array('default_data' => 'foo')));
+        $this->dataExtractor->expects($this->at(11))
+            ->method('extractDefaultData')
+            ->with($child1)
+            ->will($this->returnValue(array('default_data' => 'bar')));
+
+        $this->dataExtractor->expects($this->at(12))
+            ->method('extractSubmittedData')
+            ->with($form2)
+            ->will($this->returnValue(array('submitted_data' => 'foo')));
+        $this->dataExtractor->expects($this->at(13))
+            ->method('extractSubmittedData')
+            ->with($child1)
+            ->will($this->returnValue(array('submitted_data' => 'bar')));
+
+        $this->dataExtractor->expects($this->at(14))
+            ->method('extractViewVariables')
+            ->with($form2View)
+            ->will($this->returnValue(array('view_vars' => 'foo')));
+
+        $this->dataExtractor->expects($this->at(15))
+            ->method('extractViewVariables')
+            ->with($child1View)
+            ->will($this->returnValue(array('view_vars' => $child1View->vars)));
+
+        $this->dataCollector->collectConfiguration($form1);
+        $this->dataCollector->collectDefaultData($form1);
+        $this->dataCollector->collectSubmittedData($form1);
+        $this->dataCollector->collectViewVariables($form1View);
+        $this->dataCollector->buildFinalFormTree($form1, $form1View);
+
+        $this->dataCollector->collectConfiguration($form2);
+        $this->dataCollector->collectDefaultData($form2);
+        $this->dataCollector->collectSubmittedData($form2);
+        $this->dataCollector->collectViewVariables($form2View);
+        $this->dataCollector->buildFinalFormTree($form2, $form2View);
+
+        $this->dataCollector->serialize();
+    }
+
     public function testFinalFormReliesOnFormViewStructure()
     {
         $this->form->add($child1 = $this->createForm('first'));