According to Jamy Ian Swiss in Devious Standards, 2011, p. 122, Stuart Gordon's precise double turnover remains unpublished. (Swiss claims that Gordon executed his technique immediately after dribbling the cards, rather than from a squared deck.) The move was reportedly learned and used by a select few, such as David Roth and Earl Nelson, as early as 1974, and interpretations by Larry Jennings (The Cardwright by Mike Maxwell, 1988, p. 114) and Darwin Ortiz (Cardshark, 1995, p. 106) have been published.
Before that, Ken Simmons published the turnover in Riffling the Pasteboards, 1986, p. 8, but without mention (and seemingly without knowledge) of Stuart Gordon. It was unclear if Simmons intended to claim origination, as he prefaces the trick it appears in, “Ace-Bitiously Yours”, by writing, “You won't find any new or revolutionary moves here…” However, in Banded Deck Effects in 1991, Simmons made the claim explicit, p. 27. Subsequent research proved that Gordon preceded Simmons; see Wesley James's summary in Enchantments, 2004, p. 164.
In David Ben's Zarrow: A Lifetime of Magic, 2008, p. 341, it is stated that Herb Zarrow developed the double-card, thumb-slide technique c. 1950. This is the central dynamic of the Gordon Double-Card Turnover.