Index: includes/common.inc
===================================================================
--- includes/common.inc	(revision 6772)
+++ includes/common.inc	(working copy)
@@ -162,7 +162,7 @@
 function drupal_add_feed($url = NULL, $title = '') {
   static $stored_feed_links = array();
 
-  if (!is_null($url)) {
+  if (!is_null($url) && !isset($stored_feed_links[$url])) {
     $stored_feed_links[$url] = theme('feed_icon', $url);
 
     drupal_add_link(array('rel' => 'alternate',