12" 45 RPM records: What's the story?

So far, no one has explained just how this "pre echo" signal could be subsequently produced by deformation of the uncut vinyl, into a groove just cut, and "superimposed" on that already-cut groove with the ACCURACY of an actual cut groove, necessary to be able to identify the resulting signal (traced by the stylus,) as not only containing some kind of an "echo", but having the fidelity necessary to identify the original music signal that gave rise to it.

As for CDs, I agree with eldartford, never heard even an AAD CD with a tape print-through signal between tracks.
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Rushton...Master tape print through at the start of a selection is easily edited out when the LP is cut, or the CD data file is made. Also, FWIW, print through happens when tapes are tightly wound and stored unplayed for years. Also, newer tape formulations have minimized the problem.

Eldartford, thank you. I was aware of the cause and that newer formulations were more resistant. I'd never understood that print through was easy to edit out.

Rushton...Just to be clear...it's easy to edit out just before the music starts. It can't be removed throughout the music and is a significant problem with very old archived tapes.

Eldartford, I am gathering a number of cds and the tracks showing pre-echo.