Well, it could work in both plots:
- one where Dooku is "The Master" and Maul & Vader are his followers
Palpatine waits for his moment to take over, he has the bigger picture in mind
- the other where Sidious is the "real" master of Dooku and gives orders to him offscreen, we only see Tyrannus in what were scenes with Sidious
hm, the idea to have a Dooku, that is NOT Sith, is still interesting, it could forshadow what will happen with Anakin ...