From what I have seen is people who do not get the pop up to add the second disk seems to get game crashes and other problems. So I would say you need to get that and the second disk is needed. There does not seem to be much on the second disk - but what ever is on it - gets ride of game problems that people seem to get who don't get it to install. In my case I did get the pop up that asked for the second disk and have had no issues at all in game for the three days I have been playing it at least 12 plus hours each day.