Sessue Hayakawa's Voice dubbed?

From early in the picture I seemed to recognize Hayakawa's voice as familiar, but not his own. Then I realized it was that of Richard Loo, another fine Asian actor (The Purple Heart, The Steel Helmet, etc.). I assume Hayakawa's heavy Japanese accent was the reason for the dubbing (although he did a great job in The Bridge on the River Kwai). But I'm also led to wonder why Hayakawa was used in the first place (he was a long-standing star, of course, and that could be it). It seems as if the dialogue he had in this film was more prominent than the appearance of the actor, himself, on screen, so it could have been quite logical that Loo could have substituted for him, entirely, not only vocally. In any case, it was a weird experience to hear another actor's voice coming out of the billed actor's mouth! Overall, this was a very different kind of film that held our interest, even though it might have been a bit contrived.