Backup of Karaoke CDG's

My wife and her Sister play karaoke music at a local bar for hire. Can they legally make a backup copy of their karaoke music and use the backup copy to play at the bar, while saving the original to create another copy only should the backup get damaged?

karaoke

The copyright law gives the owner of the copyright the exclusive right to copy the material; therefore, you may not legally do so without permission from the owner.

As an exception, copyrighted work may be used for certain limited purposes by people other than the owner under the doctrine of "fair use." "Fair use" includes reproduction for specific purposes such as:
criticism and comment, including parody
news reporting
teaching
scholarship
research

I don’t believe your use qualifies under the limited purpose exception.