2002, Simon Louvish, Stan and Ollie, the Roots of Comedy: The Double Life of Laurel and Hardy, page 173
It appears clear from Stan's Joe Rock films, where he is very much in control of his material, that he had no intention of becoming part of a double act.
2005, Bob McCabe, The Authorised Biography of Ronnie Barker, page 110
Messrs Barker and Corbett were now seen as a pair. They were never a double act, never totally reliant on one another in the traditional sense of a double act, the kind that television loved so much.
2008, Jonathan Bate & Eric Rasmussen (eds.), Hamlet, "Introduction", page vii (Modern Library Edition)
Rosencrantz and Guildenstern are a double act engaged to spy on Hamlet, with the result that he has "at each ear a hearer."