Originally posted by Darth StephenMaul was a mere apprentice yet he had the title as well. In Bane's line, it doesn't matter who's the master or the apprentice, they both get "Darth."
But when Anikin was made a sith he wwas named Darth vader but he was just a mere apprentice not a sith so he shouldnt have the title of "Darth" yet.