Amazingly, there’s still new stuff coming out about Sonic 2 Beta. (See the “Hedgehog That Never Was” page in game info if you’re unfamiliar with it.)
This post on the Sonic Area 51 message board contains screenshots of 2 badniks seen in the off-center magazine screenshots but not in the beta game itself.
This practically proves that the off-center pics, including the one generally known as “Dust Hill,” were from an even earlier version of the Sonic 2 beta. Also found was a never-seen-before fish badnik.