For me the (probably incomplete list) is:
Connie Willis: Doomsday Book (three times)
Neal Stephenson: Cryptonomicon, Anathem, Quicksilver, The Confusion, The System of the World (twice or three times)
Frank Herbert: Dune (three times)
Tolkien: Lord of the Rings (three times)
Stephen King: Salem's Lot, The Shining, It (three times each)
Stephen King & Peter Straub: The Talisman (twice)
Vernor Vinge: A Deepness in the Sky, A Fire Upon The Deep, Rainbow's End (each twice)
Tracy Kidder: The Soul of a New Machine (twice)
Larry McMurtry: Lonesome Dove (twice)
Ross Thomas: Chinaman's Chance (twice)
William Gibson: Neuromancer, The Peripheral, Agency (each twice)