--- sites/all/modules/references/node_reference/node_reference.module	Thu May 12 21:40:38 2011
+++ sites/all/modules/references/node_reference/node_reference.module	Tue Jul 19 19:56:11 2011
@@ -655,7 +655,12 @@
   foreach ($references as $key => $value) {
     // We use the richer 'rendered' value rather than the raw title, but we must
     // take care of removing tags and leaving HTML entities unencoded.
-    $options[$key] = html_entity_decode(strip_tags($value['rendered']), ENT_QUOTES);;
+    if (empty($value['group'])) {
+      $options[$key] = html_entity_decode(strip_tags($value['rendered']), ENT_QUOTES);
+    }
+    else {
+      $options[$value['group']][$key] = html_entity_decode(strip_tags($value['rendered']), ENT_QUOTES);
+    }
   }
 
   return $options;