Okay, all fine.
I was an engineer in the 70s and never encountered the methods you described and no other engineers whom I knew or worked with ever mentioned them. But we learn something everyday (well I do!).
ATB.
The article and video are 21st century, Rafferty recorded the tracks referred to way back in the last century, in this instance the 1970s.
OP states that all Gerry Rafferty’s recordings were made using this ‘technique’.
Perhaps the OP was a studio technician in those days and knows something...
This is very detailed information. This so called technique would never create 4 vocal tracks (with 2 as a stereo pair from a mono voice?) plus there’d be phasing issues. Which studios, what mics, were you on the sessions?