I Learned It from Father(1964)

Clemens Andermann, once a celebrated stage and film star, now an equally successful industrialist, is firmly convinced that his son Andreas is studying chemistry in the idyllic university town of Freylangen. But he is completely mistaken. In reality, his offspring has secretly been hired by theater director Löwe to play Romeo. He would also love to play the role to his stage Juliet, the charming guest star Monika Holl. Then the telegram announcing his father's visit hits like a bombshell. Together with his friend Oskar, Andreas tries to keep the deception going by impersonating his father's doppelganger – an undertaking that initially descends into utter chaos and ultimately leads to a happy ending.