Why is Gemini classified as Derse in the Extended Zodiac when both Sollux and Mituna had both Prospit and Derse selves?

They had both Dream Selves, but they’re originally Derse- They having two and Aradia’s not having a tower makes it weird at first glance, but when you think in terms of ectobiology it makes sense. They were made in groups of six- Terezi, Vriska, Kanaya, Karkat, Gamzee, Tavros on one side, and Aradia, Feferi, Eridan, Nepeta, Equius, Sollux on the other. Hence, Gemini = Derse.