The swirling, elegant noir “Christine Falls” is the first book by Benjamin Black. Under ordinary circumstances, he might be admired for the cool precision and contemplative allure of his impressive debut. But this is no tyro: Mr. Black is the Irish author John Banville, winner of the Man Booker Prize in 2005 for “The Sea” and a man much admired for the hauteur and inventiveness of his fiction. His use of a pen name for “Christine Falls” reflects the way he has spoken about this genre novel in terms of craftsmanship rather than art.
His use of his own name in conjunction with his pen name reflects, what? A desire not to lose any sales? A desire to have two names? It's not as if he waited to see what the book's reception would be like before announcing it was his, as Doris Lessing did with The Diaries of Jane Somers. She was surprised at the time to find that only one reviewer noted a similarity in style between "Somers" and Lessing.
I know there are other authors who do this: Ruth Rendell/Barbara Vine, Anne Rice/A.N. Roquelaure, Joyce Carol Oates/Rosamond Smith, et al. The question is, why?