Exchange contacts duplicated in iCal. Outlook is not installed. Only affects iMac and does not affect iPhone or iPad also syncing same info.

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Level 1

4 points

Exchange contacts duplicated in iCal. Outlook is not installed. Only affects iMac and does not affect iPhone or iPad also syncing same info.

Hello,

I'm a bit stumped with a sync issue. The user has a new iMac (OS 15.5) and also uses an iPhone and iPad. All three devices sync an iCloud account and an Exchange Online account. Only one device, the iMac, is showing duplicates for the Exchange contacts.

Outlook for Mac is not installed on the iMac.
The duplicates do not exist in Outlook web.
The iPhone and iPad sync the same accounts but don't show duplicates.
We've tried disabling/removing/re-adding the Exchange account to the iMac and the problem remains consistent.

I'm think the issue must reside on the iMac, but I'm at a loss of what steps to take next. Any guidance or suggestions would be very much appreciated.

iMac (M4)

Posted on Jul 18, 2025 1:38 PM

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Answer 1

Barney-15E

Level 10

122,120 points

Jul 21, 2025 9:10 AM in response to MandrichKMC

Does the Exchange account have the same contacts as the iCloud account? If you have both accounts running with the same contacts in each, you will see them duplicated.

There is also the “sync” service which could be a problem. Mobile devices can use Exchange Active Sync, but desktop devices (the iMac) must use Exchange Web Services due to MS licensing restrictions. EAS is newer and better. EWS is old and klunky with various problems. I don’t know if duplicates are a known issue.

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Answer 2

Barney-15E

Level 10

122,120 points

Jul 18, 2025 4:45 PM in response to MandrichKMC

What do you mean by "iCal?" iCal died years ago and was replaced with Calendar. However, I have never seen any contacts in my calendars (but I also don't have Exchange anything). Do you mean when you add invitees?

In Contacts, is there more than one account? Do the two accounts have duplicate contacts?

All contacts are managed in Contacts. Calendar (and anything else that uses your contacts) gets them from Contacts.

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Answer 3

MandrichKMC Author

Level 1

4 points

Jul 21, 2025 7:14 AM in response to Barney-15E

Sorry. Bad description on my part. It was a long week! Contacts is what I meant instead of Calendar. They have two accounts in contacts. One is their iCloud contacts and the other is Exchange. These two accounts are sync'd to the three devices (iPhone, iPad, and iMac) but only the iMac presents this issue. We've verified on the Exchange side, that contacts haven't been duplicated. It just seems to be the way the iMac is syncing. We've removed and re-added the account, but the issue returns. II think out next step is to export the Exchange contacts, delete and re-import them.

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