The Man Who Lost Himself (1920)

Victor Jones, an American salesman, finds himself penniless and stranded in London. He meets the Earl of Rochester, to whom he bears a striking resemblance. The Earl is estranged from his wife and family, and owes a great deal of money. The Earl gets Jones drunk, changes clothes with him, and sends Jones home in his place. Jones wakes up in a daze. The Earl then commits suicide. Jones only realizes what is going on once he receives a letter that the Earl had written to him before committing suicide. Jones goes through with the charade, saves the impoverished Rochester family, falls for the Earl's wife, and ultimately confesses to the impersonation. Jones and the widow marry and move to America.