As i told in another thread. I'm pretty sure these backplates are a controlled leak. This surely is one of those old prototype 'next-gen' iPhones in an old body in order to disguise the real iPhone. It's already a known fact Apple made/makes a lot of different designs (new parts in old bodies, other way around) just to confuse people. What's with all the sudden prototype iPhones floating around? You think Apple would just let the real iPhone leaked out there?
If it was a prototype or one of many, why haven't there been more leaks of those? this is the only model that has been shown multiple times on the internet.