He does not look like Hitler, especially not like Hitler in World War I. The one on the right here is Hitler: http://imgur.com/MkWWopI

He was also apparently at Verdun from August - December of 1916. It's a message board, but is very specific about the dates.

• The picture looks like him
• He was a dispatch rider, like the guy in the picture
• He was at Verdun in 1916, which is the location and date written on the photo
• I could see why a photo like this would not have been identified as Hitler, during the Third Reich, at the grave of French soldiers for political purposes.