--- typo3/sysext/cms/tslib/class.tslib_content.php.org	2009-09-23 16:26:28.000000000 +0200
+++ typo3/sysext/cms/tslib/class.tslib_content.php	2009-09-23 16:54:51.000000000 +0200
@@ -6022,7 +6022,8 @@
 
 						$tCR_domain = '';
 						// Mount pages are always local and never link to another domain
-						if (count($MPvarAcc))	{
+						#if (count($MPvarAcc))	{
+						if (count($MPvarAcc) && strpos($addQueryParams, '&MP=') === false)	{
 							// Add "&MP" var:
 							$addQueryParams.= '&MP='.rawurlencode(implode(',',$MPvarAcc));
 						}