The Choice(1971)

When a free-spirited sailor is found murdered, his twin brother, a famous novelist, is the prime suspect. Investigators uncover a possible liaison between the dead sailor and the writer's wife, and also learn that Sayed's successful fictions owed much to the inspiration of his brother Mahmoud's adventurous life. Just as the evidence against the writer seems overwhelming, Mahmoud turns up alive. But why are the twins never seen together...?