[MTUSUPPORT]

The problem is that most likely you have imported your songs between your systems, and didn't keep the numbering of the BookId's correct. This is the only way that you could have gotten multiple BookId's without doing this, at some point.

MikeDombroski pointed this out to me. The only way to get around this is to find these files on your hard drive and delete the Duplicates. You will then have to Reimport the discs that you have duplicated.