If the box was sealed, maybe he is from a different batch that had 'Depthcharge' printed on it which was released in Japan.

However that really wouldn't be a big deal for me since back in the Beast Wars era, Takara and Hasbro releases were pretty much on par quality wise and most of their toys had high manufacturing standards. The differences were more due to artistic choice in color than anything else but I think there was no difference when it comes to Depthcharge aside from the printed name.