Twenty novels have won both the Hugo and Nebula Awards for Best Novel since 1966 (when the Nebula Award was first bestowed). The excel sheet is available here, and embedded below. Two-time joint winners are Arthur C. Clarke, Orson Scott Card, Joe Haldeman, and Ursula K Le Guin. I know that I've read four of these books (The Forever War, Neuromancer, Ender's Game and The Windup Girl), and I definitely started and possibly finished a few others in my early teens (Dune, Rendezvous With Rama, Ringworld), but Dune is the only one of those three that I remember much about. I'll be making my way through the sixteen that I never read or can't fully remember over the coming year. This is a Promise.
