This was a book with two novellas. Both novellas used the same main characters but each was written by a different author. The original novella had the characters run into a sleeping god and the robots he created to run the world for him. The robots were planning a revolt. The characters woke the god up and he killed the robots. I can't remember the second novella, but I do know it was a prequel to the original. I think the novellas were printed upside down to each other, i.e., to read the second you had to turn the book over and flip it around.