it's the same VA....it's just that he's for some unknown reason, British in all the side games but not British in the actual show, some fans theorize that it's part of a campaign to keep who Black Goku is a secret by creating the illusion that BG is a different character (like Vegeta or Frieza who both sort of have british accents....moreso frieza than Vegeta, Vegeta's is more of an ivy-league accent than a british one)