Lucille Ball wears the same outfit for two pictures
The movies "Best Foot Forward" and "Thousands Cheer" were obviously being shot at the same time at the studio, when Lucy appears in both pictures wearing the same outfit, same hairdo, same make-up. They must have trucked Lucy over to the TC set when she was shooting BFF. "Poor dear" was pulling double duty for MGM when they must have put a call out for a fill-in for the Frank Morgan skit.
Lucy first appears in BBF in the train scene, wearing the outfit in question and then in the TC skit in the same outfit.