I heard that there are books called magician the apprentice and magician the master?? I´m a little confused about this as i have only read one, and that was just called the magician.
The book we know as "Magician" in the UK was (and may still be) published as 2 shorter novels in the US. I don't know how it came about but it's the same story.
So if you've read Magician don't worry you haven't missed anything, unless you've read an early version.
I think I have an "Author's Perfered Edition" I think where Ray slipped back in some previously edited material.