Why? Westwood were probably the only game company that understood this problem, and shipped their games on two CDs (allies and soviets), even if the content was mostly identical, and could all easily fit on one, just so that two people could play at once.
It wasn't a particular problem with Westwood games, although it was when we got another player involved. I was thinking more of Age of Empires when actually saying that, I remember getting a 3-way going using a single disc.
We managed a 7-player at school, but that was using 2 discs.
