I mean technically they could be? Every canonical ship for The Untamed and MDZS would automatically populate in both fandoms if there was nothing in place to keep it from doing that. But in practice for every exchange I've been in that asks for disambiguation of noms they don't put them in both. The Untamed is a distinct adaptation of MDZS with a different timeline/different characterization/entirely new elements that aren't in the book. So I assume the nominators chose which version they wanted. It's a lot like the Narnia movies being nominated separately from the books.