Thank you for all your answers!
@vittorio: Thank you very much for the link to PM1135 on www.sovietcams.com, that's exactly the same and looks like a Princelle K92 variant not in blue but in green.
@contronatura: This was my idea too at the first look. But ... The Zorki-C in green is not so common as you wrote. It was hard to find one in good shape some years ago. The one in the picture I found years after I began the search.
@Alexander K.: A very good point! A green Zorki-1 from 1952 may be doubtfull because in this years such coverings didn't exist. But in 1955 ...
@Geoff O.: Yes, you're right, the seller from the UK had two cameras with the same s/n, one in green and one in black. But maybe it would be a good idea to take a closer look to both auctions ... the one with the green one had the correct number in the title (and was sold to me), the other one (in black) mention the s/n 55216315 in the text and you can find this s/n also in the pictures. So this auctions has nothing to do together, but the error in the title. Bye the way: Good reseach ... I didn't. ;->
Thank you very much to all. Some very interesting arguments are coming up and some misjudgments too.
Now I'm pretty shure it's probably not a fake but a real rare camera. I didn't realy imagine this after all ...
Best wishes - Guido