I don't think they really are remixing it that much. They change problem numberings and the attached online software code for the yearly new edition to prevent

I don't think they really are remixing it that much. They change problem numberings and the attached online software code for the yearly new edition to prevent students selling their second hand books to each other. Brand new titles about old Math are either trying to solve that problem or join in on it, depending on who is offering it up.