Lily and Marshall see Barney's doppelganger and weigh the choice of having a baby, while Robin is offered the job of her dreams.
This episode provides examples of:
- Batman Gambit: Lily, Marshall, and Robin use Reverse Psychology to get Ted to dye his hair blond, since they know he apparently responds to people telling him not to do something more than anything else.
- Blatant Lies: Barney pretends to be his doppelganger as a street performer so Marshall and Lily will start trying for a baby.
- Brick Joke: Marshall notes that Barney is "doing surprisingly well in the Baltics". At the end of the episode, he's approached by street performer from Estonia, which would "close out the Baltics!".
- Career Versus Man:
- Robin is offered her dream job in Chicago, meaning that she would have to move away and end things with Don. Ted at first laughs at her dilemma, because "Career has always beat Romance".
- Later, after Robin declines the offer and plans to tell Don, he is offered her position (without knowing anything about this) and chooses to take the job.
- Call-Back: The doppelgangers were introduced in "Double Date" and the gang found Ted's in "Robots Versus Wrestlers". Marshall and Lily also make their "deal with the Universe" to start having children after finding Barney's doppelganger in the latter episode.
- Character Development: Ted's speech to Robin says that in a way, everyone is a doppleganger of themselves in five years because of all their life changing decisions.
- Chekhov's Gun: While it started as a joke, Ted dying his hair blond prevented Robin and him from sleeping together after Robin broke up with Don and moved back into the apartment.
- Did Not Think This Through: Barney's plan to hook up with women while posing as a cab driver is flawed because he didn't consider that "chicks do not want to bang cab drivers."
- Identical Stranger: Lily makes a vow to start trying to have a baby once they see all the gang's dopplegangers. While Barney's doppleganger hasn't appeared yet at that point, Lily convinces herself that a guy from the hot dog cart was the remaining one, since she subconsciously tried to convince herself to start trying. The others played along after realizing this.
- Protagonist Title/Double-Meaning Title: Given Ted's speech about how people eventually become their own doppelgangers after changing over time, the title of the episode could refer to the actual doppelgangers or the gang themselves.
- Rule of Three: When Lily and Marshall are trying to have a baby, the rest of the gang barges into their room. One by one. First is Barney, then Robin, and when Blonde Ted enters...Marshall: Why is Ellen DeGeneres in our bedroom?!
- Reverse Psychology: Marshall, Lily and Robin decide to play Ted into dying his hair blond by telling him not to do it. It works like a charm and the gang use him as a Butt-Monkey for the rest of the episode.
- Rule of Symbolism: Made explicit. Lily seeing the hot dog vendor as Barney's doppelganger is used to show that she is emotionally ready to have a baby and does not need a sign from the universe.
- Series Continuity Error: On Barney's map showing the different countries of the women he's slept with, there's no check mark on Argentina. However, in "Something Blue", he mentions sleeping with an Argentinian exchange student.
- Shout-Out: The gang makes several references to blonde celebrities while making fun of Ted going blond. Barney references Billy Idol, Eminem (or rather, Slim Shady), Brigitte Nielsen, and Dolph Lundgren ("from Rocky IV"), and Marshall references Ellen DeGeneres.
