Curious thought for a story. Having a body double of myself, then both of us taking my (our?) wife.
It was a sort of mutual agreement. My wife was riding cowgirl, we got talking about her exposed arsehole. She wasn't sure who else she'd let use her arse. The only obvious answer was to clone me and have me join in.
@Gemini95 great idea! Very 'Black Mirror'. Some good potential for a twisty ending as well...