Okay, so... every original Print Shop disk shipped with a built-in backup utility which allows you to create exactly 1 protected backup, then deauthorizes the original so neither the original nor the backup could be used to make further copies.
The protection routine is tamper-checked, but this backup utility is not. And I discovered I could change 1 byte so it REauthorizes both the original and the backup it creates, so both can be used to make further copies.
No Gods, infinite masters.
@david Yes both protection systems were designed by Roland Gustafsson. They work by writing a sequence of encoded values surrounded by weakbits that change every time they're read, sometimes causing values to be swallowed/skipped on each disk revolution (but possibly seen on the next one). Nibble copiers would not properly duplicate the weakbits and would essentially "freeze" whatever randomness they had found. Protection check looked for more values than nibble copiers would find on one read.