Tried posting the book to the ISBN on the back cover: 9781617937569 and it is not in the PBS system. So checked inside the book and found a different ISBN: 9781439199619 which is in the PBS system.

My question is, why do publishers do this? Why two different ISBN on the same book? Just curious.

Edit: upon further investigation, the ISBN inside is for hard cover book. My copy is a paperback so I will be posting it to the new ISBN on the back of the book.

I have seen this situation also. It seems like the stuff on the copyright page inside is catalog in publication data and is for the first thing published which is often the hardcover. I have also seen the opposite where the isbn on the back cover is wrong and the one inside is correct.

oops

I collect Warhammer 40,000 books - some titles have 5 perhaps 6 different ISBNs and thats just for Mass Market PB's - at one point I had near 400 of these books before I noticed that I had multiple copies of the same title but they were all different ISBN - and that does not cover the Hard Backs or the Trade size coming out of England which sometimes had multiple ISBNs as well.
Now when I see a copy posted and it does not say I already have it, or that it's in my transaction file, then I have to copy the Title and do a search of my bookshelf to see if I already have the book under a different ISBN - what a mess!

Why would they do this? Bet it has something to do with money, and them (the publishers) making a few more bucks somewhere down the line from the series collectors (like me). 

I'm sure getting an ISBN established for a book title is not free - anyone have some cost factors they know about?

Covers and books are printed separately. the publishing info for one may change while the other is already done. Publishers buy ISBNs in lots, so the wrong one can get applied to different itwms.

Mass market books usually have the wrong ISBN on back and the right one inside cover. Back one is used for store inventory systems that work with publishers. Inside is real ISBN used by Library of Congress and World Catalogers.

Hope that helps.