TBH, it doesn't matter. The thing that matters, is Ryuma is seeking out the guy named "King" without knowing that King is himself. Zoro is currently fighting a King. There's also 2 Dragons in both stories, and 2 damsels in distress (Hiyori and that blond chick in Monsters). Both Zoro and Ryuma are not carbon copy, but the parralels are there.