can;t make a copy of a backup

[DOOM]

More often than not, making a backup of a backup is not a wise idea. Everytime a backup is made, there are certain anomolies (errors or deviations from the orginals) that can appear even if they are small ones and not easily noticed. These can be made worse in the copy of the copy. In most software burning manuals it tells you this. Think of it this way. Let's say that you made a copy of a VHS or audio tape, then made a copy of the copy, you would notice that the quality is degraded. CD's are pratically the same way.