fix duplex printing options

cups-pdf-postprocess.py

@@ -160,9 +160,9 @@ class CPP(QWidget):
     hbox = QHBoxLayout()
     hbox.addWidget(QLabel("Duplex:"))
     self._duplex = QComboBox(self)
-    self._duplex.addItem("None", 'duplex=one-sided')
-    self._duplex.addItem("Long Edge", "duplex=two-sided-long-edge")
-    self._duplex.addItem("Short Side", "duplex=two-sided-long-edge")
+    self._duplex.addItem("None", 'Duplex=None')
+    self._duplex.addItem("Long Edge", "Duplex=DuplexNoTumble")
+    self._duplex.addItem("Short Side", "Duplex=DuplexTumble")
     self._duplex.setCurrentIndex(1)
     self._pdfbook = QCheckBox('Use pdf&book', self)
     self._staple = QCheckBox('&Staple', self)