The more important question is which is you dominant eye?
Many people are right handed with right eye dominance but still see double sight pictures. Others are cross-dominant. If you are cross-dominant, you can turn your head so that your dominant eye lines up with the gun.
Another thing you can do is train yourself to shoot with both eyes open by applying a piece of tape to the lens of your non-shooting side eye. This will eliminate the double sight picture and for some, it will retrain your mind.
You can see the placement of the tape in this video, but transparent tape works best.
http://www.youtube.com/watch?v=XUtqZ-xjVo4