In the first match-up of pitching brothers in major league history, Jesse Barnes defeats his brother Virgil Barnes in the Brooklyn Robins’ 7 – 6 victory over the New York Giants.

On May 3, 1927 — In the first match-up of pitching brothers in major league history, Jesse Barnes defeats his brother Virgil Barnes in the Brooklyn Robins’ 7 – 6 victory over the New York Giants.

Source:
Baseball Reference May 3