Event duplication in iCloud accounts

I have had a couple of emails in the last few days in relation to Apple's iCloud and duplicates in iCal. Having used iCal Dupe Deleter the duplicates for some users are re-appearing in iCal after a short while. The addition of the duplicated events is due to iCloud re-introducing the duplicated events back into the calendars from the server.

Apple have created a knowledge base article (TS4038) that outlines how they suggest users to remove duplicates in MobileMe. This method is identical to that for iCloud calendars and (although it seems long winded) I suggest you follow these instructions when de-duping events from iCloud calendars.


Can I just say, thank you SO much! I spent over an hour trying to find a solution to having 5 of every event. Four minutes after finding your site, everything is perfect. Thanks for putting this together, it worked like a charm.

I'm glad it helped you.

I have just installed iCloud and my address book has been duplicated.

Do you have any recommendations?


Check to see if you have both your local and iCloud address books selected for display.

For duplicate contacts; open Contacts.
Look under "CARD" choose "LOOK FOR DUPLICATES" this worked instantly. now only if this worked in ICAL

Thanks John. I got rid of tons of duplicates in all the calendars following the procedures you posted here (yay) except the situation that brought me here in the first place: the calendar I created to receive dates from Dates to iCal has duplicates I cannot get rid of.

I removed that calendar both in OnMyMac and in iCloud and created a new calendar in iCloud to receive dates directly from Dates to iCal. Two copies of each event appear in that new calendar too, so obviously they are populating from Address Book via Dates to iCal. In Address Book preferences I see three accounts: one iCloud account for my AppleID (enabled), another iCloud account for my .me email address (not enabled) and one for On My Mac which on give options for syncing to Yahoo and Google (both not selected). Since I get 1 duplicate of dates from Dates to iCal, I conclude that Dates to iCal is sending both copies to the iCloud calendar. Thanks.

Your situation is not entirely clear to me. It sounds like you have two duplicate copies of your Address Book - this is why you would get two dates for each contact. If this is not what you mean then contact me using the link above.

I went to the Apple Link, on how to delete these duplicates. Am I understanding it right that I still have to put the "period" in the search and go through each duplicate one by one and delete??? Ical dupe is so much faster, but if they would not reappear. I am hoping that I am just misunderstanding the directions..

The Apple Link brings me to a page that references " MobileMe: Understanding where MobileMe Calendars are stored in iCal " at support.apple.com/kb/HT4917 but that KB article has been replaced and it's not archived at archive.org. It seemed important. Search results: no copies elswhere I could find but:

I did find three similar KB articles:

1)"iCloud: Understanding where iCloud Calendars are displayed in Calendar and in iCal" / http://support.apple.com/kb/HT4968 - and archive.org has just archived it at my request ("Here's a capture taken 0 minutes ago from the live web that will become part of the permanent archive in the next few months.").

2)Mac OS X 10.6 Server Admin: Understanding the Data Store and File Hierarchy for iCal Server - http://support.apple.com/kb/PH8431 - ditto:archived -
and while about server stuff, it had some relevant info and got me googling for ".ics file integrity checker" which got me to to http://dumitru-whoami.blogspot.com/2010/05/google-calendar-corupted-ics-... which pointed me to http://severinghaus.org/projects/icv/

3)iCloud: Resolving duplicate calendars after setting up your calendar application for iCloud Calendar - http://support.apple.com/kb/TS4118 - ditto:archived.

I haven't resolved my Calendar problems yet, but getting there. And I need to stop for the time being.

Now that I'm taking a closer look at my events, in particular recurring ones, I'm finding that Calender is incredibly buggy.

Hi Matthew,

The Apple knowledge base link described how to copy the calendars to a local calendar (under 'On My Mac') and work with it there before re-uploading. I will post the instructions to do that here later.


It's not that bad; the KB article you referenced is still there; it's one that it references that is gone.

You're a talented programmer. Kudos to you John.
Pasadena, CA.

This application ****** up my calendar. Doesn't really work in the world of ICloud

The program worked beautifully and cleaned up duplicated in my IMac. But as soon as the IMac, connected to ICloud, all the duplicates came back. ICloud overrides the IMac, thanks.
When I then started to fix the problem, I naturally made backups of my existing calendar. Little I knew that the calendar backup I save on my harddrive also comes with the Icloud account information and is therefore not a separate clean backup. So, after I had backed-up (or I thought so) my calendar on the harddrive and deleted the iCloud calendar, things got even worse.
Anyway, if you are using ICloud, be careful with this application!