In theory, all information is stored digitally, all 1's and 0's.
Copying this information to another medium should, in principle, not be a problem.
However, depending on the program and the hardware used, some errors may have been created while creating the backup. These errors will also be copied and possible even new errors added. But, it is not very likely these errors will cause any problems, mostly due to standard error correction being available.
It would always be best to make backups using the originals, but if your backups are still readable, you should have little to no problems backing up from a copied dics.