Luiz, I will take both cameras in about an hour to compare them, I have a feeling you may be right, but only in regards to the chassis itself... since the rest if all electronics in FKM-1...
Ok, Luiz, I've compared my FKM-1 to both Sokols and I've got this to say - you are absolutely right, the basic frame of the camera is identical to Sokol-2 (Sokol-1 is 1mm taller), but besides the actual chassis there are no other similarities. The mechanics and the the position of all outlets and knobs is completely different. They basically just reused the "camera" (in it's classic sense of the word, the hollow "box") for the FKM-1..