My iCal database blow up to a huge size (why I don't know). Couldn't sync etc. Found this gem and gave it a try. It found one Calendar with (get this) 12543 duplicates! My god, no wonder nothing worked. Now this process to remove the dupes took many hours, but it worked like a charm and fixed up my iCal issues. Apparently getting duplicate entries isn't that abnormal. This great utility is a must if iCal bogs down.