Photoshopped!!

Just kidding.. but seriously it does seem like a Spotmatic body cast or even parts.. but a few minor differences that I see.
1. Obviously as Aidas pointed out - lens
2. Strap lugs holes are in the wrong place on this one, Spotmatic's are positioned more front.
3. Absence of self timer - although this is debatable because you can take it off and put new leather over the hole
Assuming it is a FED SLR prototype - as a lot of things in Soviet Union they took Spotmatic as a base and maybe even used its parts to create a prototype (thus prototype) to show the bosses for approval.
Also my personal opinion - from what I've heard Leicashop's high reputation deserves benefit of a doubt, there are some very knowledgeable and respectable people who run it who know a thing or two about Soviet equipment, so I would not immediately dismiss this one.
Vlad.