Index: user_badges/user_badges.admin.inc
===================================================================
--- user_badges/user_badges.admin.inc	(revision 562)
+++ user_badges/user_badges.admin.inc	(working copy)
@@ -236,6 +236,7 @@
       $form['tid'] = taxonomy_form(variable_get('user_badges_vid', ''), $edit->tid);
       //taxonomy sets the weight to -15, so we should get rid of it to preserve the ordering
       unset($form['tid']['#weight']);
+      $form['tid']['#multiple'] = FALSE;
     }
     else {
       $form['tid']['help'] = array(