They're Off (1922)

Slats, a carefree mountain girl, and Peggy Blake, the unhappy wife of a wealthy colonel, are actually twin sisters who were separated at birth. One day while Peggy is on a trip to the mountains, she accidentally meets Slats and the two discover their real relationship. Peggy persuades Slats to take her place as the colonel's wife while she pursues her real goal, a career in the theater. Unfortunately, things don't quite work out the way the two had planned.