Back up Copy Install Discs?

Yes, you can.

There's no need to use any third-party sw, Disk Utility will do the trick.
Be careful after you dumped the image of the install media, make sure not to mount it before you burn it!

Because of it's sheer capacity it will require dual-layer media and a DL capable burner as a consequence.

Another option is to prepare your single layer compilation by getting rid of the unnecessary bloat like printer drivers, localizations, etc.
Google it, there are plenty of howto's covering this.

A third alternative is to download a pre-compiled SL installer from some file sharing service for backup purposes. If you don't go beyond what the license says and don't further share, you're not breaking the law.