HP Deskjet 6122 Color Inkjet Printer - Manual (Page 46)

2. Check Two-Sided Printing .
If the Two-Sided Printing Margin dialog box appears, click Cancel .
3. Deselect the Automatic box.
4. Select one of the binding options:
Long Side Short Side
printing instructions
Follow these instructions to print a two-sided document manually:
1. Open the Printer Properties dialog box, then select the Features tab.