Here’s a set of steps to help you resolve the issue of duplicated or overlapping appointments in your Outlook calendar:

1. Check if you have multiple Outlook accounts connected to different calendars.
2. Delete duplicate or rescheduled occurrences of the faulty event in Outlook.
3. Examine your personal and delegate calendars.
4. Resync Outlook if the problem persists.
5. Check the Outlook for mobile devices.