Dupluna

Dupluna, also known as Princess Luna or Twona, is an Alicorn mare and Princess native to the Mirror Universe.

History
Where Equestria's became resentful of her sister  and sought to seize sole control of their kingdom, the Mirror Universe's Luna became a noble individual opposed to her own $𝜇$'s dictatorship. She eventually joined $𝜇$ in fighting against her, and later befriended the Celestia of the other world and Starswirl the Bearded when they visited the Mirror Universe. Luna and Sombra enjoyed many experiences with the two visitors, with the other Celestia taking solace in Luna's company after her own sister became Corrupted into Nightmare Moon. Unfortunately, when the other Luna was restored to her former goodness, Mirror Luna fell to darkness and joined forces with her similarly Corrupted sister.

Together, the two wreaked havoc upon their world from the $𝜇$, where they were served by $𝜇$, $𝜇$, and their pets $𝜇$ and $𝜇$. After causing the ruin of $𝜇$ and other cities, Celestia and her sister set their sights on the other world's Equestria. Attacking and injuring her alternate self when the other Celestia came to visit Sombra, Celestia offered her adversary an ultimatum. In exchange for the other Celestia being able to stay with him in his world, he would allow her and Luna to travel through the Magic Mirror to the other Celestia's world. Knowing that this would mean their visiting the misery they had brought to his world upon the other Celestia's, Sombra refused, but Celestia and Luna persisted.

On their second visit, Celestia and Luna encountered the Mane Six of the other world, who attacked the wicked princesses until Sombra intervened. As a message from the other world's Luna explained, harm done to Celestia harmed her counterpart in the other world, leaving Sombra and his new allies unable to fight Celestia directly. Celestia and Luna returned to their castle, where Celestia bemoaned not learning more from her counterpart. When Luna suggested spying on the Mane Six, Celestia supported the idea, and Luna soon returned with news of their plan to encase the pair in crystal so as to not cause harm to their counterparts in the other world.

Refusing to suffer defeat, Celestia hit upon a plan to bring her counterpart back to her world and learn the spell to enter the mirror from her: she attacked her own Luna in order to injure the one from the other world. In so doing, she inadvertently shattered the mirror in the other world, and the two worlds began to merge together. The two Celestias were soon locked in combat as a result, but when the Mane Six tried to use the Elements of Harmony against Celestia, her counterpart was also affected. Refusing to allow the other world's Celestia to be imprisoned, Sombra took the Elements and used them to draw the corruption out of Celestia and Luna and into himself.

Celestia and Luna thus became noble-again in Luna's case-like their alternate selves, while Sombra became a dark entity like his own. As the worlds separated and the rift between them began to close, the other Celestia asked Luna to "take care of Sombra" for her before returning home.

Appearances

 * My Little Pony (Gameloft)
 * My Little Pony (Gameloft)
 * My Little Pony (Gameloft)
 * My Little Pony (Gameloft)
 * My Little Pony (Gameloft)