How To Stop Duplicate Calendar Entries in iCal, MobileMe, iPhone & iPad

The Problem:

You’re forced to deal with duplicate calendar (iCal) entries when you sync MobileMe with your iPad / iPhone and your Mac. The good news is; it’s very easy to remove all the duplicates. After we fix the problem, all of the duplicates will be removed.

*You can find out why it happens by following along, or just scroll down to the “The Solution…” to fix it immediately.*

FYI: This post is for MobileMe users only. If you don’t use MobileMe, this post won’t help you.

UPDATE: If you’ve switched to iCloud, here’s how to get rid of duplicate calendar entires.

Why Do You Get Duplicate Calendar Entries?

You see duplicate calendar entries because you’re syncing iCal with MobileMe and iTunes. Sounds so simple and confusing at the same time right? Let me explain…

Syncing iPhone with iCal & iTunes

When you don’t use MobileMe, you can sync your iPhone / iPad with iTunes on your Mac. This type of sync only happens when you plug your iPhone into your Mac. (See picture below.) All of your calendars are synced properly, no duplicates – yay!

Picture: Syncing iPhone / iPad with iCal & iTunes

Syncing iPhone or iPad and Mac with MobileMe

The problem begins when you add MobileMe. It’s a mess. Your data (iCal events, contacts, etc.) are syncing all over the place. From iPhone to MobileMe, iPhone to your Mac, your Mac to MobileMe AND MobileMe to your iPhone and Mac. (See picture below.)

Duplicate iCal MobileMe Events

Picture: Syncing iCal with iPhone or iPad, MobileMe and a Mac

The cause of the duplicate iCal entries is the sync between your iPhone and your Mac. There’s no need to sync iCal on your iPhone to your Mac if you use MobileMe. When you use MobileMe, you ONLY need to sync to MobileMe. Period.

To fix the problem, we have to break the sync from your iPhone / iPad to your Mac… (see photo below)

Photo: Cancel the sync between iPhone / iPad & your Mac to stop duplicate iCal events

The Solution to iCal & MobileMe Duplicate Entries and Events.

We have to stop syncing iCal when you plug your iPhone / iPad into your Mac. It’s very, very easy. Here’s how…

First we have to make sure your Mac is sending iCal info to MobileMe:

  1. On your Mac, open System Preferences
  2. Click the MobileMe icon
  3. Click the “Sync” tab
  4. Check the box next to “Synchronize with MobileMe”
  5. Select “Automatically” from the drop down menu
  6. Check the box next to “Calendars”
  7. Close System Preferences

Everything ok there? Good. (if not, look at this detailed tutorial on syncing your Mac with MobileMe)

I’m going to assume your iPhone or iPad is already syncing with MobileMe…

Now we have to break the sync between your iPhone / iPad & iTunes:

  1. On your Mac, open iTunes
  2. Plug or iPhone or iPad into your Mac
  3. Click on your device in the iTunes sidebar
  4. Click “Info” at the top
  5. UN-check the box next to “Sync iCal Calendars”
  6. BONUS: UN-check the box next to “Sync Address Book Contacts” to stop duplicate contacts! woo hoo!
  7. Click “Sync”
  8. Pat yourself on the back, crack a cold beverage, do a cartwheel and enjoy a life without duplicate iCal events.

*NOTE* You may get another set of warnings about duplicate events in iCal. However, after you manage them (merge, delete, etc) you shouldn’t get any more.

Why Does This Happen?

By default iTunes wants to sync & backup your calendar entries. Unfortunately, iTunes isn’t smart enough to know you sync your calendar with MobileMe.

I can’t find any official documentation on the Apple Support website. However, they do provide complicated solutions here and here. Unfortunately, they only solve the problem temporarily. The steps above should eliminate all duplicate contacts and calendar events permanently – as long as you keep your MobileMe account.

Written by
founded this website way back in 2007. Since then, he's owned two Macs, four iPods, two iPads, Apple TV, AirPort Extreme and 3 iPhones, is a huge nerd.