When I worked at a PC manufacturer, disk duplication was done with one of those dedicated disk duplicators mentioned above. The copy protection was copied, bit by bit, from the original file (from a floppy read into the hard drive of the duplicator), and written out bit by bit. All the bits were written out in sequence, so whatever the copy protection scheme was, it was written out just like the data was. And the duplicator machines didn't care if it was a Mac, PC, or Unix floppy originally, they all got copied over just the same way. The software to do all of that was built into the duplicator, and from what I remember, it didn't use standard floppy drives, they were modified (I think Mistumi) floppy drives with the electronics boards changed ( compared to the Mistumi drives we were using in our production PC machines). I know when a drive in the duplicator failed, we needed to get a drive from the company that made the duplicator; our standard PC drives would not work.