This article is incomplete. Please feel free to edit this article to add missing information and complete it. Reason: Voice actor info, events of EP174, an image of its four transformations from Pokémon Zany Cards, and an image of the Clefairy Ditto from the Game Corner
Duplica's Ditto first appeared in Ditto's Mysterious Mansion. Unlike most Ditto, it could not change its face when it transformed into other Pokémon, but it eventually learned how after it was stolen by Jessie, James and Meowth. It was also implied for the most part to be capable of mimicking voices slightly, as evidenced by when it managed to overcome its face problem when Ash, Misty, Brock, and Duplica attempted to retrieve it.
Duplica's Ditto appears in Pokémon Zany Cards, as a card in Special Seven mode. Playing this card changes the suit of the card to the player's choice.
When Ditto is used by Duplica, she will make a comment that she would not make when using any other card.
Trivia
Ditto's habit of not transforming its face was originally presented as an anomaly. However, likely due to the popularity of the anime, it became ascossiated as a feature of the Ditto species as a whole. Other Ditto with this trait have been seen in other media: