A user had some troubles at http://www.shsforums.net/topic/50955-help-...ster-summoning/
with his summoning limit filled up. I cannot remember where summoned creatures are stored in the save game (if at all), but I looked through his game and it appears he has 4 copies of Dire Leopard (LEOPDISU.CRE) from SR taking up his summoned slots. No idea of the cause, but I thought it would be important for you to know and be aware of if any other reports show up.
If you wish to take a look, the saved game at the link has some strange creatures in the Pocket Plane area (AR4500), including four copies each of DHARLOT1, PHEAS01, LEOPDISU, and IDJINNI, with some Move Creature effects on them. I'm not sure why this has happened, but you might have an idea since you know SR better than I do.
Edited by Ascension64, 27 October 2011 - 05:50 PM.