Min gissning är att du letar efter avsnittet Star Trek "Alternativfaktorn" , från serie 1, avsnitt # 27.
Anti-Lazarus calmly admits to stealing the Enterprise's dilithium. He informs Kirk that his people thought that two universes exist in which attempts to prove it, caused their destruction. Anti-Lazarus tells Kirk that only one Lazarus can exist in one universe simultaneously. Lazarus's time traveling ship is the "dimensional door," and connects both Anti-Lazarus and Lazarus; only by destroying the ship with the two Lazarus inside "dimensional corridor" which links the universes can both universes be saved.
Kirk confronts Lazarus, and pushes him into the "dimensional door." Kirk heads back to the Enterprise, ordering the ship's phasers to target the dimension ship. The two Lazaruses meet once more and fight as phaser beams vaporize the ship, sealing the two for all of eternity, caught together between universes.
Det finns i den "dimensionella korridoren" att omvänd bildbehandling uppträder.
Jag ser att @NKCampbell har hittat samma avsnitt ... så 2 personer samtidigt:)