Though I see that others would want to replace an established player (re: Babe Ruth).
Yeah, it's really not a huge deal for me, and Babe Ruth is the only player I've ever needed to do this with. In PS 2005, you just ended up with player cards for two different players who happened to have the same name, which I thought was fine.
The way it is now, if you start an historical association before 1919, you have to leave Babe Ruth as a pitcher for the entirety of his career--which is interesiting, too--but miss out on the batting statistics from a potential all-time home run leader. It really wouldn't be a big deal to me if it was any other player.