A Printing Preferences window from an Inkjet printer, as shown in Figure 3, will have an Effects tab or a Features tab where the duplexing options appear (Figure 3).

Figure 3: A Printing Preferences window from and Inkjet printer showing the two-sided printing (duplex) options.

A LaserJet Printing Preferences window will likely have duplexing options on the Finishing tab that appears first in the window.