The way folks used to duplicate disks protected by custom head-positioning schemes was through a variety of track-by-track copying programs (Locksmith, Nibbles Away, and Penulticopy were the most popular IIR) that could be fed parameter files with custom instructions for head positioning/rotation speed to duplicate the data for a given piece of software.

These parameter files were generally created by the community, who raced to be the first to gain fame publishing the keys for whatever just released or impossible-to-crack software came out. For a brief time, there was a thriving underground of parameter file traders.

I knew of someone who'd actually compiled a book of parameters, got it printed at a local copy shop and would sell it for $16 at swap meets. He eventually got a C&D from the makers of Locksmith claiming that the parameters he was publishing were covered under their copyright (even though they were created by the community). Not sure if they actually had a legal case, but he wasn't about to find out.