>Actually, you'd probably be surprised by the number of books written under a single pen name that are actually authored by duos.
My favourite was Bustos Domeq <g>
http://en.wikipedia.org/wiki/H._Bustos_Domecq
"The five senses obstruct or deform the apprehension of reality."
Jorge L. Borges?
"Premature optimization is the root of all evil in programming."
Donald Knuth, repeating C. A. R. Hoare
"To die for a religion is easier than to live it absolutely"
Jorge L. Borges