Diablo 2 Backup

Hi
I have 3 sons wanting to play Diablo 2(expansion set)
I have used Nero Roxio Deepburner to make a backup of the cd
so i wouldn't have em fighting ova the game.
The cd goes through the install fine but as soon as one tries to play
it comes up with "please insert expansion set cd"
i gather that ther are hidden files or something on the cd that does not copy
What else is there that i can try to get 3 backups of the cd.
By the way it is just not them that keeps looking for the cd and who has it
i keep going round to see who has it in their pc

Thanks

 

Sorry making multiple copies in this case would be considered piracy and we cannot assist with that here.