Whenever I set a category for an event (by pressing the `...` by `Categories` in the event edit screen), I get the category duplicated. This happens when selecting an existing category: I am not adding new ones. Eventually the list is just filled with copies of the category. If I manually delete these categories they also just keep coming back.
Same thing on version 5.2.3 on Kubuntu (Ubuntu plus KDE Plasma).
and the same on korganizer 5.2.3 with Mint KDE 18.1/18.2
Nice one: This was fixed *exactly* one year ago :-) First version with the fix is 16.08.1 (5.3.1). Bad news is, it won't be backported by us, sorry. If you're stuck with this version, try to point your distributor to Bug 352645 *** This bug has been marked as a duplicate of bug 352645 ***