On Sunday, the Red Sox Pedro Martinez won his 20th game. Teammate Derek Lowe has already won 21. In Arizona, both Curt Schilling and Randy Johnson have won 23, both eclipsing the magical 20 mark two years in a row.
One-or at least I-would think that two sets of teammates besting the 20-win mark would be a somewhat rare occurrence, but it's not. Prior to 5-man rotations, the 20-win mark was not as rare a phenomenon as today, so that certain combinations of 20-game winners were easier to find. For example, in 1906 six teams had two sets of 20 game winners (both Chicago teams, both New York teams, Cleveland with three, and Pittsburgh). That year there were 15 20-game winners in baseball. Even as late as 1969, four teams in the majors produced twin 20-game winners, when there were again 15 20-game winners.
I did find, however, that in the last 29 years, when five-man rotations became standard, the majors had only one other season in which two sets of teammates won twenty. Not only that-those teams were involved in what has been called the last real pennant race, with the division being decided by a playoff game. They are the 1993 Atlanta Braves and San Francisco Giants of course. The players were Tom Glavine (22 wins) and Greg Maddux (20) for the Braves and Billy Swift (21) and John Burkett (22) for the Giants. By the way, Black Jack McDowell was the only other 20-game winner that year (22 with the White Sox).