Hello, @Bryan Nash,
Welcome to the Microsoft Q&A platform!
To solve your problem, please remove the meeting from calendar. Find the invitation email from deleted items folder> Go to Outlook Web app, accept the meeting again.
If the issue persists, open your Outlook and disable Automatic process meeting requests and responses to meeting requests and polls option and check the result.
(Steps: Open Outlook: File-> Options-> Mail-> Tracking-> Automatic process meeting requests and responses to meeting requests and polls)
Screenshot for reference:
If it fails, you can try the following common troubleshoots:
1.Try removing your calendar account from the app and then adding it back.
2.Make sure both your Office and Google Calendar apps are up to date.
3.Try clearing your browser’s cache and cookies to see if it resolves the issue.
4.If you have any rules or filters set up in your email or calendar app, review them to ensure they are not causing multiple notifications to be sent.
5.Try removing your calendar account from the app and then adding it back.
If the answer is helpful please click on ACCEPT ANSWER as it could help other members of the Microsoft Q&A community who have similar questions and are looking for solutions.
Thank you for your support and understanding.
Best Wishes,
Alex Zhang