Index: modules/user/user.test
===================================================================
RCS file: /cvs/drupal/drupal/modules/user/user.test,v
retrieving revision 1.44
diff -u -r1.44 user.test
--- modules/user/user.test	1 Jul 2009 12:06:22 -0000	1.44
+++ modules/user/user.test	9 Jul 2009 19:43:51 -0000
@@ -1013,9 +1013,10 @@
    * since we cannot log in more than one user at the same time in tests.
    */
   private function insertSession(array $fields = array()) {
+    static $offset = 0;
     $fields += array(
       'uid' => 0,
-      'sid' => md5(microtime()),
+      'sid' => md5(microtime() . $offset++),
       'timestamp' => REQUEST_TIME,
     );
     db_insert('sessions')