I have a book that is on my wish list.  I have recently acquired a copy of it that is a "Book Club" copy.  Normally this doesn't bother me but I already have all 17 of the other books in the series in the full size edition so I still want to keep that book on my wish list.  Once I have finished reading it can I post the book (even though it has the same ISBN as the full size edition) without messing up my position in the wish list or will I need to offer it in the bazaar?

Yes, posting it shouldn't affect your WL. I am collecting 1st edition books from a certain author. Quite a few times already, I've gotten book club editions of his books. They have the same ISBN. I just put the book back on my WL, and repost the BC edition. 

Thank you

And hey when you post the copy you don't want-you'll move yourself up a notch.

Be careful if you are near the top of the wish list. It is possible to request a book from yourself (don't ask how I know this). Make sure you have requestor conditions turned on that you'll be able to decline so the book you post will be offered to whoever is behind you on the list.