pushing this to get an answer
Thank you for your posts.
We have been unsuccessful trying to replicate this issue. We've tried it on both Mac OS X 10.7.4 and Windows (XP, 7 and Vista) computers, and with placing the FileMaker Pro 12 and FileMaker Pro 11 folders in places other than the default locations. Still, no luck.
However, one of our Support Technicians has reported a similar case with plug-ins from a prior version being inserted into FileMaker Pro 12 runtime, so we are continuing to investigate it. When more information becomes available, I will let you know.