I finally found a solution, its a bit weird but anyways, if anyone has the same problem:
I think the issue is, that most of my contacts are doubled in my Contact App. This is because WhatsApp and Telegram create their own Account and therefore create a new Contact for every Phone Number which can be reached via the messenger.
Oh right, I can reproduce that. Once you link contacts the menues change. I'd call that a bug, there's no valid reason to let you add a picture from the main contact screen but not remove it.