It has long been rumored that MGM was not too unhappy when Greta Garbo retired in 1941. She was a truly international star and a lot of her box office appeal was in the European market which after 12/7/41 was closed off for the foreseeable future to American films. Even the past two years hadn't been easy for Garbo's or anyone else's films to be seen there.
But early in the sound era it was the tradition of several studios to make foreign language versions of their films. Garbo's sound debut in Anna Christie was accompanied by a German language version with an entirely different cast of players. All were imported from Europe. Playing Charles Bickford's part is Theo Shall and playing George Marion's role is Hans Junkermann. I noted that both had substantial careers in the German cinema. It must have been at some expense for MGM to import these people to America, but MGM had a lot invested in Garbo and they wanted her career in sound to last.
Salka Viertel better known as a writer played Marie Dressler's role and she stayed in America. Her credit in Anna Christie is under her maiden name of Salka Steuerman and she was of left wing persuasion, enough to be blacklisted. But that was way in the future.
These folks were quite up to their English language counterparts. Garbo of course is eternal and so is Eugene O'Neill in the themes he writes about. Watching the German language version is further proof of the care that MGM took with Garbo's career.
She was in fact one of a kind.