--- book_manager.module	2010-05-12 13:57:45.000000000 -0700
+++ book_manager.module	(working copy)
@@ -253,7 +253,7 @@ function _book_manager_outline_remove_ac
  * @return int The uid of the bid author or 0 if this is not a book
  */
 function _book_manager_get_book_owner($bid) {
-  if ($result = db_query("SELECT n.uid, n.nid FROM {book} b LEFT JOIN {node} n ON n.nid = b.bid WHERE n.nid = %d GROUP BY n.nid", $bid)) {
+  if ($result = db_query("SELECT n.uid FROM {book} b LEFT JOIN {node} n ON n.nid = b.bid WHERE n.nid = %d GROUP BY n.nid, n.uid", $bid)) {
     $row = db_fetch_array($result);
     return $row['uid'];
   }