Help! Duplicate Entries on My iPhone.

I recently had this problem and thought I’d share the solution. I have a .me account for my Macintosh that syncs with my iphone. My iPhone had duplicate iCal and Address Book entries even though my computer did not. The trick is to completely replace everything on the cloud (.me) and your iPhone and replace with your computer’s contents.

1. Go ahead and backup your address book on your computer in case something goes wrong (Address Book / File / Export / Address Book Archive). Trust me on this one.
2. Delete the MobileMe account on your iPhone (Settings / Mail, Contacts, Calendars / Select your .me account / “Delete Account”). Choose “Delete from my iPhone”. This could take a minute or so.
3. Turn off your iPhone completely.
4. Login to your .me account (me.com) and delete your address book and all of the contacts, groups, etc.
5. On your computer go to System Preferences / Mobile Me / Sync / Advanced
6. Select your computer and choose “Reset Sync Data”. Choose to replace all your information or just your address book, calendars, etc. (depending on what you want to replace and are having issues with) and choose the right arrow pointing to the cloud (“On MobileMe with sync info from this computer”) This is going to replace everything on the cloud with your computer information — so make sure you are happy with what is on your computer. Choose “Replace.”
   
7. Restart your iPhone.
8. Create your Mobile Me Account again and set it to sync the items you want synced — Settings / Mail, Contacts, Calendars / Add Account…”
9. Turn on everything you want to sync. You will get a message saying there are existing records; Select MERGE data. It’s a good time to turn on “Find My iPhone” as well. Select “Done”. Wait a minute until it finishes configuring.
10. Wait for 10 minutes until your iPhone has time to sync.
11. Check to see if it is all working as expected.