i'm syncing contacts and calendars through MobileMe and have duplicates of everything. there's this "All on my Mac" or "All on my iPhone" toggle, but if i'm using MobileMe, shouldn't they both be the same?
Removed all of your MobileMe info from your phone. When it prompts you, select the options to remove all contacts, cals, etc from your phone. After it does that, go look at your calendar. Hopefully, it's blank, if not, you'll have to delete what's there. After you have your calendar/contacts wiped out from your phone, then re-add the MM info, and it should sync with the "cloud" and you should be good.