Apparently, these are well know problems with Entourage putting duplicates everywhere. There is even a FAQ topics on duplicates thanks to Joe for the pointer. Now maybe I can get rid of the 30 entries for St. Patricks Day in my calendar.
There is a simlar set of utilities of iCal that google:”ical duplicates” and Hawkwings.net and John Massey which has now become a Cocoa application as opposed to just a script. This deduper works like a charm. Wiped out half of the dupes in iCal!!!
For Address Book, there is a builtin deduplicate function and for Kerio
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