Here are a couple of screenshots from iCal. In each case, one event on
one calendar got duplicated a gazillion times between four different
It happened a couple of different times. one time I fixed it by doing a search for the title, selecting all results and deleting; the second time I just deleted the offending calendars, which got spuriously created by the syncing process anyway — between iCal, Entourage, Plaxo, .Mac, a Treo, an iPhone, and maybe some other devices or services. Having this mass of baloney records in a database just makes syncing go slower and worse over the course of months.
I hope somebody (everybody) fixes this soon. There should be warnings or alerts or errors or something when potential duplication is going to happen.