Using Microsoft Calendar efficiently can help keep your events organized. Here are some steps to try to help resolve duplicate events on the Calendar:

1. Check the primary event source – If you have multiple accounts connected to the calendar, check to ensure that a duplicate is not being created on the primary calendar.


2. Disable synchronization for the secondary calendar. – If your primary and secondary calendars are connected via synchronization, try disabling the sync.


3. Check Third-Party applications – Third-party apps such as mail clients can produce duplicate calendars, check the access permissions of third-party applications


4. Reset the calendar cache – This will help to clear out any remaining duplicate events.