The Disreputable History of Frankie Landau-Banks, by E. Lockhart
I think the titles are far too similar!
The Septembers of Shiraz, by Dalia Sofer
It doesn't help that both books are listed together on the Orange longlist of 2008 so I always read their titles at the same time, they also both conjure images of the Middle East.
The Imperfectionists by Tom Rachman
The Sentimentalists by Johanna Skidsrud
Both were award winning books (Giller Prize Winner for Skidrud and NY Times Notable List and Giller longlist for Rachman) and have the same type of title.
What about you? Do you confuse these pairs of books? Are there others that you confuse? It is actually really hard to come up with these, because you don't realize that they are two different books!