Sigh.
For DECADES, there was a data recovery firm offering rewards for EXACTLY what you state. They were never claimed.
Magnetic history is absolute, 100%, anti-science, tosh. There's no way that a piece of magnetic material remembers where it used to be, or that you can recover - statistically or probabilistically - overwritten material on a magnetic medium.
This is EXACTLY the kind of tosh I'm talking about. Military specs were based on "making sure", not on the bare minimum necessary. It's cheaper to write over it ten times "just in case" than take the risk that someone finds a way. Nobody ever has. Seriously. Go look. It's tosh.
https://link.springer.com/chapter/10.1007%2F978-3-540-89862-7_21
Biting the hand that feeds IT
