I'm not really going to help much. My Pulsus has a 218D in it but I have no idea whether it is the original movement. I am 100% sure my dial/movement is not in the original case. It should be in a gold tone case but is in a SS one. I have purchased a couple of gold 218's with the idea that I would put it into them but, when I got them, decided not to cannibalize them.
I agree that it is very strange to find a 2185 in one and would just about bet that it is not the original movement.
My guess would be that Alton1 has already answered the question.