lol. using 'back up' cds to play PSII games is an excellent idea if your children are too hard on the original cds. just be aware and make sure if it is legal in your country then you are completely safe.
i am saying this because in our country, using a mod chip is now legal and therefore our children are so much lucky.
hope site site would be helpful to you.
http://www.psreporter.com/mod-chip.html