Oh wow, it was so long ago, back in the early days of digital TV when we had a channel I think was called BBC Choice (eventually became BBC 4), I suspect it was on there. It had animations that looked kinda like the London Underground. As far as I remember it was a series that focused on the relationship between various bands and musicians, but I only saw a couple of episodes, the last one I saw was about Lou Reed, the Velvet Underground, Andy Warhol and David Bowie. It was like a family tree if that makes sense.
But what it was called and where it aired, I can't be totally sure. I never looked it up as I had heard it was Bob Dylan from at least two sources, I just accepted it as fact.
There's been various times though that I've seen these kinds of documentaries and they've gotten things wrong. I sometimes wonder if it's an anti plagiarism measure.
If you are sure it was someone else, I'm perfectly willing to accept you are right
I just talked to my dad as I'm sure he saw the series too and he felt like he'd also heard it was Bob Dylan that created the guitar overdub, but since I had introduced an element of doubt, he wasn't 100% sure.