Dimensional Counterparts

A dimensional counterpart (似た者同士 Nitamono dōshi, lit. Fellow look-alike) is a phenomenon featured in the Yu-Gi-Oh! ARC-V anime, in which a person from one dimension resembles another person from another dimension. In addition to sharing the same face, the counterparts are drawn to each other due to their connection with certain two individuals, Zarc and Ray.

History
Before the existence of the Four Dimensions, there's a world where all summoning methods existed, which is known as the Original Dimension. In this dimension, lived two individuals: the Duel Champion and superstar Zarc and Leo Akaba's daughter Ray. As Zarc reached the top of Dueling world, his thirst to attain god-like power drove him to destroy the world together with his Four Dimension Dragons. He was stopped by Ray who used four cards and Dimension Bracelets created from Earth's natural energies. The clash between them caused each of their souls to be split into four fragments and each were reborn in the newly existed four dimensions. Zarc's fragments are: Yūya Sakaki, Yūto, Yūgo, and Yūri. Ray's fragments are: Yuzu Hīragi, Serena, Rin, and Ruri Kurosaki. Leo's plan, Revival Zero, is fusing the four girls so he can revive Ray.

Mistaken Identities
A common recurrence is for a character to confuse one counterpart with another counterpart due to their identical facial structures. Instances of confusion include:

Zarc
Zarc is known as the Demon Duelist and Supreme King Dragon Zarc,  who once nearly destroyed the whole world undefined  and caused it to be split into four dimensions. After his defeat, his souls were split into four together with the original dimension and these four souls reborn as four boys who each resides in each four dimensions. Like Zarc, each of his counterparts has a Dimensional Dragon and their connection with Zarc allows them to sync their mind with each other. Zarc, who still seeks destruction, constantly influence Yūya and his counterparts through a rampant state of mind called The Awakening that usually triggered when they are greatly angered or the dragons are summoned at the same place and time. By entering this state, Zarc slowly tries to consume their souls so he can be reborn. Each of the counterparts are capable of absorbing one another. This can be done in two ways: Willingly becoming one with the other or the counterparts Duel and the loser will be absorbed.

Ray
Ray is the girl who stopped Zarc from destroying the whole world and her soul were also split into four dimensions. Similarly to Zarc's counterparts having Dimensional Dragons to help signify themselves as counterparts, Ray's counterparts are wearing unique jeweled bracelets that contains Earth's natural energies. For this reason, they are collectively called Bracelet Girls (ブレスレットの Buresuretto no Ko). Their Decks are also created from the four cards with the same natural energies that Ray used together with the bracelet to defeat Zarc. These decks are based from Japanese proverbs, Kachō Fūgetsu  which literally means: Flower, Bird, Wind, Moon. The bracelets they possessed became some sort of radar, the gems will glow if Zarc's reincarnations are in one place and about to become one. In Yuzu's case, her bracelet has an ability to transport Zarc's reincarnations to prevent them from gathering in one place, most likely to stop Zarc's revival.

Trivia

 * In Japanese, both male and female Standard and Fusion dimensional counterparts are sharing same voice actor/actress. The male Standard and Fusion counterparts are voiced by Kenshō Ono, while the female are voiced by Yūna Inamura.
 * In English Dub version, all the male dimensional counterparts are voiced by Michael Liscio Jr..
 * In English Dub version, all the female dimensional counterparts are voiced by Emily Bauer.
 * The Fusion dimensional counterparts are the only ones who have no relation with each other.