AceSEF will continiously genereate SEF URL if any non-SEF URL is routed to it and that non-SEF URL doesn't exist in AceSEF's URLs list unless you've entered any part of the non-SEF URL to "disable-SEF" variables.
ItemID is one of the most important and problematic part of Joomla! and SEF, check out the OSTraining tutorial for more info about what is ItemID http://bit.ly/chjojc
Some duplicates or increased ammount of SEF links that may be undesirable may be caused by other variables used for ordering, sorting, etc. These can be also excluded from the SEF URL and reappended behind it.
