Comment 1 for bug 1353599

To solve this problem you must add one line in scanner.vala (line 933) and add the string "Duplex" to the adf_suplex_sources array:

 string[] adf_duplex_sources =
                {
                    "ADF Duplex",
                    Sane.I18N ("ADF Duplex"),
                    "ADF Duplex - Long-Edge Binding", /* Samsung unified driver. LP: # 892915 */
                    "ADF Duplex - Short-Edge Binding",
                    "Duplex"
                };