Samsung M262x Benutzerhandbuch (en)

Mac printing
3.  Special Features
Printing on both sides of the paper
Some features may not be available depending on models or options. It 
means that the features are not supported (see "Variety feature" on page 7).
Before printing in the duplex mode, decide on which edge you will be binding 
your finished document. The binding options are, as follows:
Long-Edge Binding: This option is the conventional layout used in book 
Short-Edge Binding: This option is the type often used with calendars.
From your Mac application, select Print from the File menu.
Select Layout from the drop-down list under Orientation
Select a binding orientation from the Two-Sided option.
Select the other options to use.
Click Print and the machine prints on both sides of the paper.
If you print more than 2 copies, the first copy and the second copy might 
print on the same sheet of paper. Avoid printing on both sides of paper 
when you are printing more than 1 copy.
Using help
Click the question mark on the bottom-left corner of the window and click on 
the topic you want to know about. A pop-up window appears with information 
about that option's feature, which is provided from the driver.