Bioware Community Coordinator Chris Priestly writes:
Yes, there are 2 game discs for both the PC and Xbox 360 versions, both the Collector's and standard editions
The PC version is a standard install. You install the information from both discs and then play with 1 disc in the drive. No swapping
The Xbox 360 does not have an install and does require disc swapping during play
Even though there is a disc swap, it occurs at a carefully planned place in the game (that does not interfere with gameplay) and is done once. You do not swap back and forth. 1 swap and then done