--- modules/user/user.module	Thu Apr 23 14:52:35 2009
+++ modules/user/user.module	Thu Apr 23 14:52:07 2009
@@ -428,7 +428,7 @@
       // make it permanent.
       if (($picture->status & FILE_STATUS_PERMANENT) == 0) {
         $info = image_get_info($picture->filepath);
-        $destination = file_create_path(variable_get('user_picture_path', 'pictures') . '/picture-' . $account->uid . '.' . $info['extension']);
+        $destination = file_create_path(variable_get('user_picture_path', 'pictures') . '/picture-' . $account->uid . '-' . time() . '.' . $info['extension']);
         if ($picture = file_move($picture, $destination, FILE_EXISTS_REPLACE)) {
           $picture->status |= FILE_STATUS_PERMANENT;
           $edit['picture'] = file_save($picture);