Click the
Tools menu Merge KMA Files command to add
KMA files on your hard drive into your existing Songs Database that were not imported directly. This preserves your current Songs Database and printed Song Books while adding new KMA files that were not imported directly into the Songs Database.
While merging, if a BookID is found that already exist in the Songs Database, the BookID in the KMA header of the file being merged is renumbered to the lowest free BookID available.
This is from the Hoster Manual and I believe it will fix your problem.