I've been syncing my iPhone over the air directly my Exchange server which worked perfectly. After installing iTunes 9 I noticed the options, "Sync contacts with: Outlook" and "Sync calendar with: Outlook." I checked both boxes. Now I have duplicates of every calendar item and every contact. Apparently the iPhone considers the items it synced from my PC different from those it synced over the air. I now have two calendars. One it calls "on my phone" the other it calls "craigrow@xxx.com." The same is true for contacts, two groups, "on my phone" and "craigrow@xxx.com." 😟
Prior to firmware version 3.0, you could sync contacts and calendar events over the air with an Exchange account and/or with a MobileMe account, or direct with the supported application on your computer via the iTunes sync process. You could do one or the other, not both at the same time.
Apple added the ability to do both beginning with firmware version 3.0 for those with an Exchange account syncing business contacts and calendar events over the air with the Exchange server who are also interested in syncing personal contacts and calendar events direct with the supported application on their computer via the iTunes sync process.
To get rid of the duplicates, deselect sync contacts and calendar events direct with Outlook under the info tab for your iPhone sync preferences followed by selecting Apply.
On your iPhone, go to Settings > Mail, Contacts, Calendars. Select your Exchange account. Turn Contacts and Calendars off for over the air syncing. This will erase all contacts and calendar events downloaded over the air from the Exchange server with a warning message provided indicating this will occur, but this will not erase the contacts and calendar events transferred to your iPhone direct from Outlook via the iTunes sync process.
Wait a minute or two for your Exchange online contacts and calendar events to be deleted from your iPhone.
Follow this by turning Contacts and Calendar events back on for over the air syncing with the Exchange server. You will be provided a merge prompt, which you can select.
Thanks Allan. That worked. Somehow iTunes got into a weird state where the Sync calendar and contacts boxes were not checked so I had the check them, sync, then uncheck and sync. I never would have thought to delete the over-the-air items to make the phone delete the local items. Weird, but fixed. Thanks again.
I had a duplicate calendar problem as well from syncing with two macs and an iPhone. I followed the simple turn off calendars, wait, and then turn it back on. The iphone then prompted me to merge with MobileMe and voila no more duplicates.
Discovered same problem in contacts and after turning off contacts, deleting the contacts off my iPhone when prompted, waiting and then turning it back on, merging with MobileMe worked an removed the duplicates contacts.
Thank you Allan - 41,656 posts is impressive! This one helped me.
Follow-up Q --
Following this method, when I turn AS back on, the prompt I get is "Do you want to delete the Contacts/Calendars on this iphone?" I assume that's the "merge" prompt you mention, but which should I do?
When I chose delete, it seems to have removed almost all events from my iphone's calendar. But the deleted events show in ical on the Mac, and I have a backup from today. What's best way to have them all AS back onto the iphone?
Update --
Most, but not all the items reappeared on the iphone from ical. But not all. And new ones I create in ical don't seem to be transferring over.
If my Mac info is right, but phone incomplete, is there a good way to start from scratch w/ Exchange AS, ensuring all ical items get transferred to iP?
I have had this same issue using my Microsoft Exchange account. I cannot get the duplicates to stop happening when I go through these steps (i.e. turning the on-air syncing back on after unchecking the I-tunes sync). I am not getting a "merge contacts" option, just "delete" or "don't delete". What should I do?
When I turn contacts and/or calendars on, I get the "What would you like to do with existing local contacts on your iPhone"? message, with the options of "Keep on my iPhone", "Delete", or "cancel".