This writer's name is actually Carlos Ruiz Zafón.
Spanish naming convention is that the forename is followed by the father's surname, which is optionally followed by the mother's surname.
Wikipedia describes this custom as "historical". I've often thought that in these times of women choosing to retain their own surnames after marriage, and so many children being born outside marriage, the Spanish tradition is far superior to the widespread use of double–barrelled surnames. The point is that both surnames tend to be used for official documents, but for everyday use (including, I would suggest, on footballers' shirts) you can choose which one you want to use.
Wikipedia (as you might expect) has more information than you could probably need on this subject.
The Shadow of the Wind is set in Barcelona, in the period following the Spanish Civil War.
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