Each game you should have 2 players play 48 minutes at C and PF (1 at each position). Don't put a starter and backup in, and then switch them in the second game to balance the minutes. The reason for this is because if you switch them in the second game, it is unlikely that the minutes will be split the same. So you might end up with 2 players on 50 minutes and 2 players on 46 minutes after the second game.
Goodluck!