Phillies game not recorded on correct DVR channel

I've set my DVR to record all Phillies games.  Several times now, a Phillies game was broadcast on BOTH TBS and Comcast Sportsnet and was only recorded on the DVR on TBS, and of course what showed up on the screen was that the game was blacked out because of league contractural agreements.  Why does it not record the game on BOTH channels, and is there a way to specify the channel I want the game to be recorded on (Comcast Sportsnet)?

Thanks!