Different titles for the same book (American and UK editions), are evil. This is the second time recently, I've accidentally ended up buying a book I already have. This time, it's book 2 in the Obsidian Mirror/Chronoptika series, by Catherine Fisher. I already had The Box of Red Brocade and wrongly assumed that Slanted Worlds was book 3. Unfortunately, it's still just book 2 and I could already have owned book 3. Also, apparently, it's not a three but a four books series. How confusing. Or is it just me being stupid?

Source: http://umrion.net/crimson/?p=2836