If there was some sort of guarantee that each entry would recieve several votes, then this would work. But the voter turn-out is an unknown variable and should be dealt with as such.
If say:
thebleakness entered all three images, but only recieved 3 votes (one vote for each image) He would officially only get 1 vote even though he really got three.
I think that one entry per-person will be the best move for now.