Let's have a look at the Twin Digimon, Terriermon and Lopmon!
Although only referred to by their baby names, Gummymon and Chocomon, both Terriermon and Lopmon had their debut in the Movie Digimon Adventure 02: Vol.1 Hurricane Touchdown!!/Vol.2 Transcendent Evolution!! The Golden Digimentals.
[If you have only seen the English Digimon The Movie, I highly recommend watching the japanese original for each of the 3 movies cut together for it. This movie alone has about 50% of its content cut.]
Most of you will easily remember Terriermon, but Lopmon only shows up in its child form in this ending illustration done by the late Yasuo Ōtsuka.
Instead of Kenji Watanabe or other Bandai staff, Terriermon and Lopmon were designed by the movie's director, Yamauchi Shigeyasu himself, for the movie.
On the design sheet, we can see several points in which Terriermon and Lopmon were supposed to be distinct from each other in their body style. On this sheet, Terriermon is 1.7 heads tall, while Lopmon is 2 heads tall. Even if they would fall straight down, Lopmon's ears also appear to be shorter than Terriermon's. Lopmon's visible canine is a design element still used today, even though in terms of size and proportions, the twins are identical in modern media.
Due to its popularity from the Adventure 02 movie, Terriermon was chosen as partner for Jianliang Li/Henry Wong in the next anime season, Digimon Tamers, and by association, Lopmon was chosen as partner for Jian's sister Xiaochun/Suzie.
According to the Reference Book, Lopmon is the lonely crybaby type, while Terriermon is calm and robust. Both have the move Petit Twister, while Terriermon's signature move is Blazing Fire and Lopmon's is Blazing Ice. Furthermore, the Reference Book entries of their Baby I stages Zerimon and Cocomon state that they're the only Digimon that are born as twins, but the reason why is still unknown. They also aren't exclusively born as twins and can hatch alone from eggs individually as well.
On the Digimon Web Twitter, Terriermon and Lopmon appear on various occasions, including the celebration of ふたごの日 futago no hi Twins Day. (5th of February)
The Card Game also features them together on some of their cards! And there's even official card sleeves with the two.
Both of them appear to be very popular and are featured in many parts of the franchise, Lopmon in particular, being chosen as a partner Digimon for characters in a number of games.
