Mille, Marie og mig (1937)

Ellen "Klaus" Klausen/Marguerite Viby moves to the city to study medicine. As an orphan, she must work on the side to support herself. She's popular with the other students at the women's student dorm. Her single anatomy professor doesn't date his students. He sees her singing at a cabaret, but is led to believe, that it is Klaus's sister, Mille, an understandable mistake as he meets a completely different personality without glasses. The professor meets her again, where she's a maid at a dinner party as she was fired as crooner for slapping a customer. This time she's the simple, rural sister, Marie.