Edit: Had a look at my writeup in my blog [0], Lastschrift it was. Amazon picked a bank account that did not exist anymore to pay for the order. When that bounced came the fees - and while one fee for that would have been normal if I had given the wrong bank account (which I'm pretty sure I only did, if I did, because their system did not save when I changed the bank account before), to take multiple fees for one order was in no way okay.
[0]: https://www.onli-blogging.de/1832/Meine-richtig-schlechte-Su... (in german)
You'll have to ask the banks why. In my case it wasn't a problem, but technically it shouldn't happen and it's strange that it did.
That added to my concern with Amazon just using the wrong bank account, and that old account occuring again and again in my profile. Even if I wanted to order something at Amazon it would be too risky now.