Sources
Ryan Shriver
Matt Schofield

The Grateful Dead played Hollywood Bowl on 7/21/74, and one eyewitness places the end-time of that show at about 9pm. It's doubtful, but not impossible, that Garcia flew right back to the Bay Area to catch a late set with Merl. Even if they played together on this date, it almost certainly wasn't at the Keystone in Berkeley, which was headlining Moby Grape, with Earthquake opening. There's also the little matter of "When I Die" (initially designated "Jam #5" as a placeholder title), which appears twice here. It's possible that this was a gig at a more out of the way place such as the Sand Dunes (if this is, indeed, ca. July 1974) or The Generosity (if this actually dates, as one might conjecture, to the first half of 1975). See the JGMF post "JGMS: July 21-22," 1974, Keystone, Berkeley, CA" for more conjecture, and, for more on the Sand Dunes, "Jerry with Merl and/or Martin, ca. 1974, The Sand Dunes".