Index: hierarchical_select.module
===================================================================
RCS file: /cvs/drupal-contrib/contributions/modules/hierarchical_select/hierarchical_select.module,v
retrieving revision 1.160
diff -u -F^f -r1.160 hierarchical_select.module
--- hierarchical_select.module	21 Mar 2009 20:07:46 -0000	1.160
+++ hierarchical_select.module	27 Mar 2009 23:05:27 -0000
@@ -656,6 +656,12 @@ function hierarchical_select_process($el
   * Hierarchical select form element type #after_build callback.
   */
 function hierarchical_select_after_build($form, &$form_state) {
+  // TRICKY: Pageroute compatibility: avoid that the body of this #after_build
+  // callback is executed twice.
+  if (isset($form['hs_form_build_id'])) {
+    return $form;
+  }
+
   $names = _hierarchical_select_store_name(NULL, NULL, TRUE);
 
   if (!isset($_POST['hs_form_build_id']) && count($names)) {