Needs help burning already 'burnt games CDs'

My brother has asked me to burn some 'burnt' game CDs he obtain from one of his friends. When I try to 'copy' the CD Nero stops claiming that the format is invalid or something like that.
Can some one please provide me witht the right settings for Nero to burn the CDs.

Did I mentioned that the games I'm trying to copy are 'burnt copies'?
I just want to make sure.

Thanks