I had fun with this, in my head. Imagine the following: an NFL team had to sub in, for one of their players, at any position, TWO exact copies of you (so they'd be allowed to have 12 men on the field in this case). Is there any position at which they'd be better off, even for a single play?
For reference I am a decent athlete, have never played organized football, and am short and skinny.
For me the first thing that came to mind was wide receiver...it would be an extra person to cover, you could have a 5-wideout set and block like it was a 4-wideout set, for instance. However, when you consider that 1) it might be easier for two players to single-cover me than to double-cover an NFL wide receiver 2) catching an NFL pass is probably be harder than it looks and 3) I might break in half if I was tackled, then I am not so sure.
I think that rushing the passer on an obvious passing down is the only possibility, at least for me. They would have to block the two of me with two players, and if they didn't, even if I failed to catch or tackle the QB I could certainly make it more difficult to throw the ball down the field.
I don't know if anyone else finds this kind of thing fun to think about, but if you do, please chime in.