all the fic I wanted to write but didn't

No one's ever tried to cure a demon inhabiting its own body before. When Sam cures Dean, things go awry and they end up with two Dean's - one human, one demon.

Dean's of the opinion they should kill demon Dean but Sam won't let him. He wants to try again.

Dean is concerned they'll end up with more Dean's so Sam does more research. The new cure involves communion wafers and human Dean's blood, and the result is successful, except now they have two human Dean's, completely identical.

Potential for deancest or a Sam sandwich.