Two popular authors have just signed new two-book contracts with their respective publishers, proving you don't always have to move on to be well paid. They are young novelist Brad Meltzer, who re-upped with Jamie Raab at Warner, in a deal worked out with agent Jill Kneerim at Boston's Hill & Barlow agency; the new titles will follow his The Millionaires, due out in January, and Warner's Rob McMahon will continue as his editor. At Little, Brown, bestselling humorist David Sedaris has renewed his arrangement with publisher Michael Pietsch for two more, including a book of humorous essays along the lines of his big hit Me Talk Pretty One Day. Pietsch bought North American, book club, audio and electronic rights from agent Don Congdon.