How to Enable Double-Sided Printing on Navigator Forms

Navigate to Setup > Forms Designer.

Locate the form you want to enable for double-sided printing and double-click to open it.

In the bottom right corner, select the Dictionary tab.

Click New Item and choose New Variable.

In the Variable Name field, enter DuplexPrint (note that it is case-sensitive), then press Tab to auto-populate the Alias field.

Press OK to add the variable.

Once this is done, your form will be set up for double-sided printing. As long as your printer supports duplex printing and this feature is enabled, any form with this variable will print on both sides.