A method and a system for double-sided printing of a series of sheets is provided. First printing data for being printed onto a first surface of the series of sheets are provided. The first printing data comprise a plurality of first subsets, each first subset for being printed onto one sheet. Second printing data for being printed onto a second surface of the series of sheets are provided. The second printing data comprise a plurality of second subsets. Each second subset is associated with a respective first subset. A first print is printed in dependence upon the first printing data onto the first surface of the series of sheets. A second print is printed in dependence upon the second printing data onto the second surface of the series of sheets. The first print is scanned and first print data in dependence thereupon are provided. The second print is scanned and second print data in dependence thereupon are provided. For each sheet the first print data and the second print data are processed to determine if the second print data are associated with the respective first print data and data indicative thereof are stored in a database.