Calendar Categories problem

with Netrunner 17 finally Kontact is complete again. But it looks like the Calendar categories have a problem. The old problem that the chosen color for categories were not stored is solved. But now the used category is displayed in the list 3 times after I used it once for an event. When I use it twice it is shown 5 times in the list and so on. How can I fix this? Or is this a bug?