Index: tests/Zend/Form/Decorator/FieldsetTest.php
===================================================================
--- tests/Zend/Form/Decorator/FieldsetTest.php	(revision 24811)
+++ tests/Zend/Form/Decorator/FieldsetTest.php	(working copy)
@@ -229,6 +229,20 @@
                                 ->render('content');
         $this->assertContains('<fieldset id="fieldset-id"', $html);
     }
+    
+    /**
+     * @group ZF-10803
+     */
+    public function testFormIdOverridesFieldsetId()
+    {
+        $form = new Zend_Form();
+        $form->setAttrib('id', 'form-id')
+             ->setView($this->getView());
+        
+        $html = $this->decorator->setElement($form)->render('content');
+        
+        $this->assertContains('<fieldset id="fieldset-form-id"', $html);
+    }
 }
 
 // Call Zend_Form_Decorator_FieldsetTest::main() if this source file is executed directly.
Index: library/Zend/Form/Decorator/Fieldset.php
===================================================================
--- library/Zend/Form/Decorator/Fieldset.php	(revision 24811)
+++ library/Zend/Form/Decorator/Fieldset.php	(working copy)
@@ -131,7 +131,7 @@
         $name    = $element->getFullyQualifiedName();
         $id      = (string)$element->getId();
 
-        if (!array_key_exists('id', $attribs) && '' !== $id) {
+        if ((!array_key_exists('id', $attribs) || $attribs['id'] == $id) && '' !== $id) {
             $attribs['id'] = 'fieldset-' . $id;
         }