Duplicate birthdays in Calendar but only on Mac

Solution 1:

macOS Catalina (10.15.7)

Unchecking and renabling birthdays on the calendars sidebar will only toggle visibility and did not remove the duplicates, but unchecking and renabling 'Show birthday calendar' in the calendars settings seems to reload it - that's what worked for me.

Solution 2:

I also had this issue once. If it only occurs on the calendar of macOS but not your iOS devices and you use a sync service like iCloud check this setting:

1. On your Mac open Contacts.
2. In the menu bar select "Contacts" > "Preferences…"
3. Select "Accounts".
4. Verify that all listed accounts are listed only once.
5. To disable an account temporarily, select it and uncheck "Enable this account".

If you have identified the account that resulted you may remove it with the "—" button on the bottom left.

Let me know if this solved your problem.

Solution 3:

I was suffering the same issue (under Yosemite 10.10.5 on this MacBook) and just now resolved it via iCal's "Calendars" sidebar by unchecking "Birthdays" and checking (ticking) "Contacts."

Note: I sync my calendar via Google Calendar, and --after years of resisting-- linked my Apple Contacts to Gmail. "Birthdays" in my iCal sidebar is at the very bottom of the list, right under "US Holidays."

Hope someone finds this helpful.