I don’t know how old many of you are, but what Charlie described was known in the late 60s and early 70s as ‘sound on sound’. This layering was done with reel-to-reel tape decks, and it was a big deal.
It also was the forerunner of effects we routinely hear now in live performance. I had a device called an Echoplex, which was a short tape loop. I could play duets with myself during a solo.
I'm old; been there - done that! I hated splicing tape!
I had a Dynacord Echocord:
https://www.youtube.com/watch?v=kiBeTGL-eCkThe same tape loop idea as your Echoplex.
Along with echos I could get the sound the Stones used in Satisfaction by turning the volume up on it and down on my amp. I attracted a lot of guitarist back then using that technique. Today the amp's gain control is used.
Things have really changed for the better haven't they?