From the fantastic This Day in Baseball Tumblr comes this very interesting statistic.
In a match up of 300 game winners at the Philadelphia Baseball Grounds, the Phillies’ Tim Keefe beats Pud Galvin and the Browns, 2-0. The next time two National League pitchers with 300 or more victories will face each other will occur in 2005 when Greg Maddux of the Cubs beats Astros ace Roger Clemens 3-2.
It took 113 years for the National League to have opposing 300 victory pitchers face each other in a Major League Baseball game.
Source: This Day in Baseball