George and gduns are correct. As long as all the disks were assigned different BookIDs, there should be no problem combining them all into one folder.
However, you want to be careful that your friend didn't add any of HIS disks to YOUR database. Unless you have an original copy of every disk that has been imported onto your hard drive, you can be held responsible for the copyright infringement.
MTU has a page explaining the copyright laws. You can click
here to review them.
- Alan