There is a section in my webcomic where the main character, while still on his planet (he is an extraterrestrial who ends up on Earth), is a double spy and assassin. I thought of an idea for a arc in that story: he ends up spying on himself from both sides. He will have to fake killing himself while convincing everyone that the two versions of him are different. I have a number of possible further complications to his situation (for example: a duel love affair of two of his fake identities by a different double spy who suspects they are the same but not sure and plays along with the charade to not blow any of either spy's identities's covers). I also have to have his identities to compromised and for him to have the feeling that all his lies are coming back to haunt him... This "spy in the mirror" idea might work well in that part but at the same time, if he succeeds at pulling it off, it could work at the beginning to help him get cocky about his skills as a spy.