CBS

Season 5: Episode 24 - Doppelgangers

Doppelgangers: Marshall and Lily make a secret pact that when they finally see Barney’s doppelganger, they will start trying to have a baby since it will be a “sign from the universe”.  So far the gang has seen “Lesbian Robin”, “Mustache Marshall”, Stripper Lily, and "Mexican Wrestler Ted."  They think they see “Cab Driver Brunette Barney” but it turns out to be the real Barney scamming for girls. We learn that Lily still has reservations about having a baby.  Robin and Don have recently moved in together.  She is offered an anchor job in Chicago and decides to turn it down because she wants to give their relationship a chance, and does so without telling Don.  Don is then offered the same job and he takes it, thus moving to Chicago and breaks Robin’s heart.  Meanwhile Ted has dyed his hair blond, determined to prove he can pull it off.  A few months later Lily really sees Barney’s doppelganger.  She pulls the gang out of the bar to show the “Hot Dog Vendor Barney”, and although in reality he actually doesn’t look much like Barney, Marshall gets that this is a sign that she is now ready to have a baby, and the gang goes with it.