Elapsed appointments double

Hi, sorry for my bad english first.
I got a problem with my Nextcloud calendar. I created some repeating appointments and Iā€™m syncing the calendar with my iPhone. After the appointments are finished, they show up twice on my calendar. I got the same Issue with my OwnCloud before. Does anybody know, how to fix that?
Many thanks in advance!

Can you specify what you mean with show up twice?

Can you please provide proper reproduction steps and name the expected and actual behavior.
Maybe add some screenshots.