Benes Envy or My Dad Cannot Beat Up Your Dad-It's Physically Impossible
Brothers Andy and Alan Benes face off tonight in the Cards-Cubs game in St. Louis. It is believed to be the only the seventh time that siblings have pitched against each other in major-league baseball history. The last time was in 1996 when the Martinez brothers, Pedro (Montreal) and Ramon (Dodgers) faced each other.
The five other possibilities that I found follow (with the years each started a game in the same league, but no the same team, in brackets):