Personally, I would ask champ if the extra CD is included. When I bought my copy from VGM World, the bonus CD was packaged separately. It had its own slimline case, catalog number, and everything. You can see it here:
http://vgmdb.net/album/6114
I guess what I'm saying is that it is possible that champ is selling just the Gyakuten Saiban 3 soundtrack. So if you want the extra disc, then ask before you buy it.