History Main / OnlyOneMeAllowedRightNow

* ''{{Futurama}}: Bender's Big Score'' had this in effect. When ever a duplicate was created through time travel the universe would kill them off to prevent further confusion. However, at the end of the movie, several hundred time-traveling Benders appear simultaneously; this proves too much for the universe to handle, and a hole in space-time rips open.

* In the ''TheLegendOfZelda: MajorasMask'', no matter how many times you go back in time, there is only ever one Link (and Tatl) in Termina.

* In ''[[{{Ptitle7hpv9q0i}} Nth Man: The Ultimate Ninja]]'', it is impossible for a person to be in two places at once. This causes one character to spontaneously combust when she returns to the past, as she arrives at the same time she's being born.

* ''CastlevaniaJudgment'' is a borderline example. While Aeon is able to face himself in battle, he specifically states that it will cause damage to the timeline.

* This turns out to be a major plot point in {{xxxHoLic}}; [[spoiler: the main character]] is a time travel duplicate. As a result, he hates himself and draws in supernatural beings trying to grant his wish and kill him, and if he doesn't develop strong social connections he'll soon cease to exist as reality corrects itself.

** As that universe is a StableTimeLoop where paradoxes are stopped by the universe disallowing the trip to happen at all, a better way of looking at ToSayNothingOfTheDog is that retrieving him from the past would have killed his future self, probably resulting in his dead body causing a paradox. Would you go back in time if you knew you'd get almost immediately killed there? So the net, stopping a blatant paradox, simply wouldn't open to let the past version back. Sadly, this trick only works in the near recent past...killing yourself by doubling up would work just fine when you were far enough in the past that your dead body wouldn't be identified as you.

** ''The Gates Of Hell'', a fan written DnD book, features a devil who can travel in time. If he tries coming too close to his alternate self, he is pushed back and stunned.

* In the ''Time Scout'' series, you can't travel to a time where one of you already exists because you'll wink out of existence on arrival.

* Played straight, and quite awfully, in ''TimeCop'', where matter which touches itself in a different time is destroyed. This becomes mind-boggling when [[spoiler: the bad guy from the future is made to touch the his past self ''wearing a jacket'', and both are destroyed]]. Or did they expect us to believe it was the same jacket ?
** Isn't this NeverTheSelvesShallMeet?

* In the [[MirrorUniverse Mirror Realm]] of ''AdventureQuestWorlds'''s 2nd Birthday Event, the hero that you play is chosen to save the Mirror Realm because he or she is the only person in the entire multiverse who does not have an alternate in the Mirror Realm -- if anyone else in either world were to go to the other world, they'd have to switch places with their mirror counterpart. Paul and Storm do not have mirror counterparts either because they "grew up in a small suburb just outside of the multiverse." [[{{MST3K Mantra}} Just roll with it]].

* This applied to the DCUniverse [[PreCrisis before the first Crisis]]. If a character traveled to a time where he or she already existed, it (the version not belonging to that time) would become an invisible, unheard, ineffectual phantom until it stepped out of that moment in time. Note that, even if characters were allowed to "meet themselves" history could ''not'' be changed back then, so it was pointless anyway.

* In ''SevenDays'' when Parker goes back in time, the Parker from the time he goes back to disappears from existence.

Note that this is NOT NeverTheSelvesShallMeet. In that one, you can have millions of copies of a same character running around in the same universe without that much trouble, only they must not meet each other. In this case, even though there are only 2 copies and they are at the opposite side of the universe, the problem still happens

* Played straight, and quite awfully, in ''TimeCop'', where matter which touches itself in a different time is destroyed. This becomes an extreme WallBanger when [[spoiler: the bad guy from the future is made to touch the his past self ''wearing a jacket'', and both are destroyed]]. Or did they expect us to believe it was the same jacket ?

Note that this is NOT NeverTheSelvesShallMeet. In that one, you can have millions of copies of a same character running around in the same universe without that much trouble, only they must not meet each other. In this case, even there are only 2 copies and they are at the opposite side of the universe, the problem still happens

* ''{{Homestuck}}'': According to Aradia, a future self who goes back in time is doomed to be destroyed by the universe sooner or later.

* ''LesVisiteurs'': Godefroy's ring and the museum's start heating, and eventually fuse together.