The double R2R2R is rarely done. The fastest is by Jim Nelson, 22h48m on 11/6/1999. The following additional quad crossing information is courtesy of Davy Crockett: Previously, Wally Shiel established the quad record on 10/4/1987, with a time of 24h45m. Others who have completed quad crossings are Dana Miller (1994), Susan Gimbel (1994), Davy Crockett (2006), and Jason Vaughn (2013) who did 43h31m on his way to the first ever triple R2R2R.
A poster "hyperphil" reported more about Miller's 1994 R2R2R2R2R:
"Dana Miller did the quad in 1994, not 1993 (I was with him). He was shooting for a sub-24, but got very nauseous on the last crossing, puked his guts out all the way up the SK to the finish. He was the first one to do it, though."