[ballenf]

I don't think it was mentioned, but I wonder if the mains power fluctuation (voltage or hz) would affect drive sector length / rpm also? So even the same drive couldn't produce a high fidelity copy of one of these discs if the power input was different.

[xxpor]

I'm not sure how good the power supplies were back then, but ideally you'd have no idea what the mains power was at the drive since the power supply converts everything to DC. Now of course rectification isnt perfect so there were probably some artifacts, but enough to detect on the disk? Seems unlikely.

[phnofive]

Seems like intentionally randomizing this would be a good way to mass produce fingerprinted copies - in addition to any variants in the media.