Until you get it in hand, only the seller knows.
I'm leery of stock photos w/little to no descrip on this particular poster.
Did you ask if it was double-sided?
Unfortunately "double-sided" isn't enough to determine if this Dark Knight poster was authentic or not, because double-sided fakes did/do exist for it, courtesy of MovieGoods. I realize the subject of this poster has been discussed over and over but when the market began drying up of the authentic ones, dealers such as MovieGoods were offering reproductions of it. A customer of mine brought it to my attention when he noticed it being offered on their site but it didn't state "original item" and as everyone knows, MG doesn't bother to state if their items are reproductions, but most know they are. He got a response back from them and was told the posters were in fact reproductions and were double-sided. I decided to email them under a new email address and inquire myself, and was told they were a specially made reproductions and double sided.
When I saw on eBay a few sellers adverting them for sale, I inquired as to where they got their copies and all of them said basically the same thing, they had ordered one from MG thinking it was a reproduction but because they were sent a "double-sided" one they assumed it was the real deal sent by mistake so each of them said they wanted to make money on the poster and ordered more from MG, some saying they got a quantity discount, and then figured they had legit posters, when in fact, they had reproductions they were selling. I remember them never selling a movie poster again after that, all had admitted they had no knowledge of the poster industry but wanted to make money off collectors by offering the poster.....which turned out to not be legit.
