A list of contacts rife with duplicates can be a plague in one’s technology experience, especially when they contain different information. It’s often mysterious how an address book can become so cluttered.

I think this condition is often caused by syncing devices with cloud accounts and/or different default accounts on each of multiple devices.

Start With a Backup

Before making sweeping changes to your contacts, it’s a good idea to take a backup. If something goes awry with merging duplicates or consolidating accounts, a backup will restore your address book to its previous state.

Since the Contacts database is located in a challenging spot and consists of multiple files, the Contacts app provides an easy way to generate a unified backup file that includes all contacts, groups, group membership, and distribution list settings.

In the File menu of the Contacts app, select Export > Contacts Archive… and choose a place to save the file.

Look for Duplicates

In the Card menu of the Contacts app, you’ll find the command Look for Duplicates. This command has long struck me as one of the more unconventional names in macOS. Additionally, using it arguably requires a healthy dose of trust. Read on…

To Merge or Not to Merge

The interface of searching for duplicates and subsequently merging them is quite minimal. When you run this command, which is available on the Mac and not on iPhone or iPad, the resulting dialog leaves much to the imagination.

In my case, Contacts found 7 duplicate contacts. The meaning of this, as described below the result: duplicate cards have the same name but different information. Here are two cases in which Contacts will not conclude that two contacts are duplicates, even though they appear to have the same name:

  1. One first or last name actually has an extra space before or after a name
  2. You entered someone’s first and last names together as their first name in one card and separately in another

If you click Merge, you can only hope that Contacts will eliminate duplicate contacts without corrupting your database. Okay, don’t be so worried. Unless Contacts finds hundreds of duplicates, you’ll probably be fine. After all, you started with a backup, right?

Sadly, though, this operation might be more trustworthy if Contacts would add some transparency about its findings. The app already offers an interface for preventing duplicates when importing contact cards. I’ve sent feedback to Apple requesting that it additionally implement this interface for reviewing duplicates before merging.

A possible reason not to merge would be if you have a number of old contact entries whose information is out of date. If it’s possible that you’ve retained contact info that is no longer valid, you may want to search for and review your duplicates manually, or contact me for additional guidance.

[Update: As of iOS 16, iPhone and iPad can detect duplicates to merge. As there’s no menu on these devices, they reveal the presence of duplicates automatically and offer a similarly simple opportunity to merge them.]

As I mentioned earlier, one possible culprit leading to duplicate contacts could be different default accounts on each of multiple devices. Take a look in Contacts > Preferences > General on the Mac and Settings > Contacts on iPhone/iPad. If you have multiple Contacts accounts, one of the choices is Default Account.

If, for example, Google/Gmail is your default account on iPhone while iCloud is the default on Mac, you might have inadvertently created contacts in different accounts and might even not see the same full list of contacts on both devices.

If this is the case or if you’re having trouble making heads or tails of it, I recommend contacting me for an assessment and for help resolving the issue and consolidating your contacts.