--- formfilter_orig.module	2008-12-15 18:54:44.000000000 +0000
+++ formfilter.module	2010-08-31 16:30:48.578125000 +0100
@@ -119,6 +119,8 @@ function _formfilter_filter_element(&$el
   foreach (element_properties($element) as $key) {
     switch ($key) {
       case '#tree':
+      case '#id':
+      case '#name':
         continue;
       default:
         unset($element[$key]);
@@ -127,7 +129,7 @@ function _formfilter_filter_element(&$el
   // Set final form of array.
   if ($value) {
     $element += array(
-      '#type' => 'value',
+      '#type' => 'hidden',
       '#value' => $value,
     );
   }