If, and before you click on link, I must advise you that what you will see will not be Pretty.
Just testing out my photoshop skills.
I have figured out all the angles and lighting to make any one person "look" like two (or twins) and be with themselves.
Threw the idea around and was told the it was incest and illegal. I have done it with both girls and guys, and have lots of content. The reason for the examples is mainly because I don't think anyone will sue me for being with myself.
http://www.sicklisa.com/maletwins.htm