Currently Being ModeratedFeb 11, 2013 10:26 PM (in response to Al.from Cal)
If you are syncing your calendar with both iCloud and iTunes, that will cause duplicates.
Currently Being ModeratedFeb 12, 2013 2:44 PM (in response to randers4)
iCloud is turned off for iCal and I can't use iCloud with my Mac because I'm not using a new enough version
Currently Being ModeratedFeb 12, 2013 3:00 PM (in response to Al.from Cal)
I believe to fix this you'll first need to reset the SyncServices folder on your Mac, as discussed here: http://support.apple.com/kb/TS1627. Then clean up the duplicate enteries in iCal, and make sure it contains all your events so you can replace the calendar on your phone with your iCal calendar. Next, without connecting your phone to your computer, open iTunes and disable automatic syncing by going to File>Devices and checking "Prevent...from syncing automatically". Now connect your phone to your computer, click on the name of your phone, go to the Info tab of your iTunes sync settings and confirm that you have selected to Sync Calendars with iCal. Then further down under Advanced...Replace information on this iPhone, check Calendars. Then click Apply at the bottom to sync your phone. This will replace the calendar on your phone with the clean version in iCal.
Then, prior to syncing again, back up your iCal calendar by opening iCal and going to File>Export>Calendar Archive. Try syncing again and see if it finally stops creating duplicates.
Currently Being ModeratedFeb 14, 2013 12:25 AM (in response to randers4)
Thanks very much. This seems to have solved the problem. I tried it several times and iCal seems to have copied correctly.