When I put events on my MobileMe calendar, syncing causes numerous duplicates to appear Anyone encounter this, or know how to prevent it?

I'm syncing two MacBooks, an iPad and two iPhones.

Each entry appears one to five times once it syncs.
For each of the devices remove the MobileMe account and opt to delete all the data when asked (it usually asks if you would like to remove the data associated with that account). Then add back again and see if it continues.