Once upon a time there was a episode set on Cordelia's birthday known as Birthday This episode gives some meta on what would have happened if Cordelia never joined the AI team. Why does this matter? Because this meta is exactly what Doyle will be coming from in his mirror self.

Birthday we find out Cordelia was never meant to get the visions thet only passed because Doyle truely loved her when he kissed her. She gets the chance to give them up the past and go back to become a famous actress. Its kind of just another reality. She's famous and she ends up realizing somethings wrong and hunts down the AI team. Angel's chained up in a room muttering incoharently because he lost his mind as Wesley stated "When he watched his only friend Doyle jump to his death after being passed the visions." ....but to pass the visions love and a kiss is needed...

SO! Everyone can enjoy Doyle being all up on the vampire and convinced that Cordelia is a big time actress, Outside of that he's pretty much the same just small changes. I'm going to say he's from a few hours before he died in Hero to just keep him from freaking out over dying for the course of the event.

PLZ be having fun with him!