fuzztone, I attended the same Lyn Stanley AXPONA 2018 seminar. Apparently the tape was made simultaneously with the DD, cut as a safety copy. From the Lyn Stanley web site:
The original session used RGMI 468 1/4 inch tape at 30ips as the lacquers were being cutI actually own both the DD and tape. Although the DD LP is truly exceptional, the tape is even better IMHO. Clarity, resolution, frequency response, low noise, spatial presentation and dynamics are second to none to my ears. The best recording I have ever heard!

