World Why Dooku and not Tyrannus?

[Hobgoblin]

Whenever I hear people talk about that character, they refer to him as Dooku. It's like people referring to Sideous as Sheev. Tyrannus just sounds cooler. Dooku always does me think of dookie.

 

[Mr. Peanut]

Because he's barely ever referred to as Tyrannus in the films or TV show.