By mid-1958 everything RVG recorded was in stereo. All the mono releases after that point were fold downs.
Don't have time right now to find the references but the fold-down myth has been comprehensively debunked. RVG's early stereo mixes are downright amateurish in comparison to mono. Laughably so, in fact, in comparison to the cohesion of the mono versions.
There is simply nothing to beat mono done well, and if you think the image all collapses to the centre, then you haven't heard it done well.
Walter Legge, probably the finest producer of classical recordings of the entire 20th century, believed stereo was a fad that detracted from the music, and a lot of early stereo bears that judgment out - gimmicky left-right panning is no substitute for the incredible depth and transparency achievable in mono and it took quite a few years before the trick of 3D was properly mastered (and even then, 'done well' wasn't - indeed isn't! - universal).