SOLVED - can't remove duplicate birthday in Calendar on Macbook

I had duplicate contacts on my Macbook (but not my iPhone), and consequently duplicate birthdays in my Calendar on my Macbook (again, not my iPhone). I would delete a contact on my Mac, but it would delete the contact from my iPhone. I didn't know how this happened, and I didn't know how to fix it. I was having a hard time searching a fix online and I was going in circles.

Eventually I figured out how to fix the duplicates in my Contacts (fix below), but duplicate birthdays in my Calendar remained. When I tried to manually delete a birthday it told me I had to remove the birthday in my Contact card, but that contact didn't exist anymore (I had removed the Gmail duplicates), so I was stuck. I searched and searched and SEARCHED to fix this issue with no luck. It was frustrating because I could see other people had the same issue but I was never able to find a fix.

Today I accidentally found the fix! I want to share so hopefully this helps a few people from pulling their hair out over this.

DUPLICATE CONTACTS:

I learned the duplicates came from my Gmail contacts (so I had iCloud contacts and the duplicate Gmail contacts). I'm not sure how or when I synced my Gmail contacts ... but I was able to unsync them and this resolved my duplicate contact issue. I don't remember where I found instructions to do this, but you should be able to find it online. Seems like I had to physically log into Gmail in a browser on my Macbook and stopped sharing birthdays. Also open your iPhone and check ... Settings > Privacy & Security > Contacts ... make sure Gmail is unchecked.

DUPLICATE BIRTHDAYS IN CALENDAR:

1. On your Macbook open Calendar.
2. Go to: Preferences > General ... uncheck "Show Birthdays calendar", then recheck "Show Birthdays calendar"

Seems like removing the Gmail contacts should remove the calendar birthdays automatically, but it doesn't. And for whatever reason, turning birthdays off and back on again did the trick.

I hope this helps!

P.S. I'm not sure if I'm posting this in the right place. Please tell me where to post a fix if it should be somewhere else. This is all I could find.