Amazon says this for The Ultimate - " The ultimate treat for Sudoku fans. This is a new collection of 150 unpublished puzzles of all levels......" and this about book 3 and book 2 "....This book contains over 100 unpublished puzzles with four levels of difficulty. ......." (emphases mine).
I would assume that they are all original and unpublished but those contained in the New York Times books, for example, may contain a puzzle (or more) that's been seen here. Not that I'd notice, myself.
I'd like to know for curiosity's sake too, but reckon that the best way to find out is to PM Wayne.