Thicker Than Water (1935)

Oliver's in trouble with his wife after missing a payment on their furniture, having given the money to Stanley, who used it instead to pay Mrs. Hardy for his room and board. At Stan's suggestion Ollie then withdraws the couple's savings from the bank to pay for the furniture and inadvertently pays virtually the whole amount at an auction for a grandfather clock which is soon crushed under a passing truck. Mrs Hardy then unintentionally causes serious injuries to Ollie requiring him to be rushed to hospital for a blood transfusion. The doctor conscripts Stan to be the unwilling blood donor. Problems occur with the transfusion and when Stan and Ollie leave the hospital they appear to have morphed into each other.