I had someone offer me 2 credits for a book that is hot on a lot of people's wishlist right now and that I have.  (Not on my bookshelf but in my possession).  I had someone else tell me that more than one credit per book is against the rules.  Does anyone know, is this true?

I'm sure someone more knowledgeable then I will pop in and give you the skinny on the situation. But I'm curious as to how this person knew you had the book at all?

Because they simply asked if I had any on their wish list.....

It's against the rules. 

Here's the link to the Help Center:  Can I offer/ask more than 1 credit for a book?

However, you are perfectly free to post your book directly to a specific member's wishlist.

...What Rhonda said :-)

No one can offer or ask for more than one credit, the site would boot both people off if they caught such a transaction. Someone can, after the fact, buddy an extra credit as a thank you, but any negotiation prior to the order is an absolute no on this site.

Yup, that's a BIG no no on PBS.