Error 400 Ambiguous URI path separator

HTTP ERROR 400 Ambiguous URI path separator

URI:	http://raago.no/404/index.php%3Fmanufacturer_id=28&route=product%2Fmanufacturer%2Finfo?manufacturer_id=28&route=product%2Fmanufacturer%2Finfo
STATUS:	400
MESSAGE:	Ambiguous URI path separator