Funny you should mention about the 7DII images being like two slightly displaced images - I have had that feeling for sometime but never mentioned it. I usually put it down to the effect of the anti-aliasing filter everyone complains about. Yours is the first reference I have seen about it. I have also sometimes put it down to my Dell 4K laptop screen (Not my best purchase). A bit of sharpening and contrast seems to give me a better illusion when I see this problem. Oh hell, Jeff - you have just put more doubt in my impressionable mind.
Ray ... life is to short to be shooting and testing and playing with a peace of tech from a group that is in business to make money. If it ain't perfect get you another one.. I'm going to.