Lonely Wives (1931)

Richard Smith (Edward Everett Horton) is a married lawyer, but he has a penchant for seducing women. When Richard meets Felix (also Horton), a comedian who looks exactly like him, the two hatch a plan. Richard will allow Felix to impersonate him on stage if Felix is able to convince Richard's mother-in-law that he is actually Richard. Meanwhile, Richard tries to seduce Felix's wife (Laura La Plante), and Felix fools Richard's wife, Madeline (Esther Ralston), into sleeping with him.