I'm thinking part of the reason for the name change was to "Americanize" himself to get more work as an actor. I believe there are others that have done the same thing, though none come to mind.
Back in 1991 I went to a Sci-Fi Convention to see actor John Levene. He's known to Doctor Who Fans as Sgt. Benton of U.N.I.T. While talking with him I found out he had acquired a "stage name" of John Anthony Blake saying it was more of an American name. I don't know offhand if it worked though...
