--- og.module	2012-07-03 14:34:51.000000000 -0400
+++ og_fix_create_error.module	2012-07-03 14:32:02.000000000 -0400
@@ -1049,9 +1049,10 @@ function og_group_membership_invalidate_
  */
 function og_membership_create($gid, $entity_type, $etid, $values = array()) {
   // Make sure the group membership doesn't already exist.
-  if (og_get_group_membership($gid, $entity_type, $etid)) {
+  // If it does, return the membership data.
+  if ($membership = og_get_group_membership($gid, $entity_type, $etid)) {
     $group = og_label($gid);
-    throw new OgException('OG membership for entity ' . check_plain($entity_type) . ' with ID ' . check_plain($etid) . ' for group ID ' . $gid . ' (' . $group . ') already      exists.');
+    return $membership;
   }
   $values['entity_type'] = $entity_type;
   $values['etid'] = $etid;