According to the game's director Tatsuya Nakae in a 2000 Arcadia magazine #3 developer interview, he was asked why the team included two Wolverines in the game, one with bone claws and the other with adamantium claws. He commented that the team wanted to focus on the bone claw Wolverine, but the directive from Marvel was that both had to be included in the game. This made it difficult for the team to differentiate the two characters as they look almost identical, so they had to think of where and how to add pronounced, yet subtle differences.
Contributed by ProtoSnake