#2 has a real singlepoint for sure (though I would've numbered them the other way-I'd call this #1).
I'm pretty sure this is also the one currently in a private collector's hands. It's currently missing the front barrel/receiver, front scope, and singlepoint.
I believe the private collector lonepigeon is referring to is David Oliver from propmasters.net You can find a VERY small picture of the gun under "The David Oliver Collection" at that site.
Here is a resized version:
After finding this, I wrote David and asked if he would mind making any better photos available. He responded:
"sorry, no. the photos of my collection on my website are purposely small to prevent replica makers."
I continued to question him about his gun. he wrote:
"both guns were actually 'cut down' for promotional shots after filming. The prime photo example is in one of the uk poster magazines from 1977 which features the guns (inc. mine) in it's shortened state as mine is today.
i obtained mine indirectly from the publicist some 16 years ago."
Just for reference, according to what David wrote, he received the gun around 1987.
The poster magazine he is referring to is the one I have posted earlier in this thread. You can clearly see in that poster that one of the guns is "cut down." It is possible that the second gun is cut as well, but you can't tell due to it going off the side of the poster. From what I can tell, if there were ONLY two MG-15s used in ANH, it appears David's gun is the one on the left in the poster magazine due to the similarities in the eyecap on the snooperscope (which appears to be slightly different on each gun).