diff --git a/taxonomy_single_tag.module b/taxonomy_single_tag.module
index a92eecb..2f6f6a0 100644
--- a/taxonomy_single_tag.module
+++ b/taxonomy_single_tag.module
@@ -89,8 +89,12 @@ function taxonomy_single_tag_form_alter(&$form, $form_state, $form_id) {
             }
           }
           // avoid default multiple tags description 
-          if (empty($vocabulary->help)) unset($element['#description']);
-          array_unshift($form['#submit'], 'taxonomy_single_tag_submit');
+          if (empty($vocabulary->help)) {
+            unset($element['#description']);
+          }
+          if (!in_array('taxonomy_single_tag_submit', $form['#submit'])) {
+            array_unshift($form['#submit'], 'taxonomy_single_tag_submit');
+          }
         }
       }
     }