Sometime during December 1970 and January 1971 there were 2 shows per night. One at 9:15 and the other at 10:15. It's probable that one was live and the other was a rerun of a previous broadcast.
(On the 4-3-71 (rerun) show he announces a time change to 10:15 which did not get edited out - dating the original broadcast to sometime in Feb 1964)