Index: Image.php
===================================================================
--- Image.php	(revision 11372)
+++ Image.php	(working copy)
@@ -335,7 +335,33 @@
      */
     public function generate()
     {
-        $id = parent::generate();
+        // try count for unique name generation
+        $trys = 2;
+
+        do {
+            $id = parent::generate();
+
+            // file does not exist, exit loop
+            if (!file_exists($this->_imgDir.$id.'.png')) {
+                break;
+            }
+
+            // a file with that name exists, retry
+            $trys--;
+        }
+        // do until trys are used up
+        while(true === (bool) $trys);
+
+        if (false === (bool) $trys) {
+            /**
+             * @see Zend_Form_Exception
+             */
+            require_once 'Zend/Form/Exception.php';
+
+            throw new Zend_Form_Exception("Unable to generate unique filename.");
+        }
+
+
         $this->_generateImage($id, $this->getWord());
         
         if (mt_rand(0, $this->getGcFreq()) == 1) {