Several days before we broke the news on the Old Republic novel, a fan on the Star Wars Message Boards asked Lucasbooks Editor Sue Rostoni whether the Old Republic novel, the Sean Williams novel, and the September 2010 novel were one in the same or if they made up more that one item.  At the time, Sue could only comment that they were more than one book.

Knowing now that the Williams and Old Republic books are one, we can conclude that the September 2010 book is something else.