Confluence team calendar sends out duplicate notifications for a single event

[Georgia]

My team has a Confluence calendar. Every time any event happens, every subscriber to the calendar receives two identical email notifications about the same event type. The duplicate emails are received seconds apart.

Example: If tomorrow is Sally's birthday, today everyone on the team receives two emails in a row reminding us that it is Sally's birthday.

How can I fix this? Is the solution simply to scrap the calendar and restart?