This is a questions about titles matching exactly.  I started to post the book Prelude to Foundation by Isaac Asimov. 
The ISBN match was
Prelude to Foundation (Foundation, Bk 6)

These are the same book.  Prelude to Foundation, though a prequel to other books in the series, was the 6th book published in the Foundation series.  But, one of the things I have learned on PBS is that recipients tend to be rather picky (although I personally have never been RWAP'd).  Since the cover art doesn't match I was concerned that someone who expects cover art to match, would use this slight title difference as an excuse to RWAP.

If you were the recipient of this book would you consider it to be a title match?

Since there are already 93 copies in the system, I think I will forego posting, but decided to pose the question anyway.

Absolutely post it. The part in parenthesis is just added to let people know where that book is in the series and it is not part of the book's actual title. Something like that is rarely printed on the book itself. If it is, it might just be on the spine in small print.

I read a lot of serials. I see this all the time. I have never expected that to actually be on the book.

Since you say it IS the 6th book in the series published, the title is not actually inaccurate so it should be fine to post. I would be concerned about a non-fiction book when we are dealing with editions, but not on a fiction book and series information. Calling something the 7th edition of a text when it is really the 4th can affect the content someone is expecting. Calling a fiction book the 6th in a series doesn't change the version of the story they'd get.  If you want to make sure people understand it is a prequel, you could submit a data edit to make that information clear in the description.

Yes, it is a PBS convention that the series information (if any) is labeled in parenthesis after the title. I have never heard of anybody confusing that with the actual book title.

You can submit data edits to make the titles match by adding the series info the title of your edition and others missing that info.The you have it mentioned in you post is the way they want it shown  Title (series title, bk#)  It helps people when ordering and helps to link all the book editions to each other. The data edit button is under the More Options button on the book details page.  You can fill in any other info you see missing when you submit a data edit. Data editing is done by volunteers so it's a help to PBS when you submit accurate, needed data edits.

That's a PBS courtesy, not part of the official book title.