You can set a Preset so that whenever you print, you just have to choose the option and it will print double sided.
On this case, use Textedit as a tool.
-Open TextEdit
-Click File then Print, the print dialogue box will appear
-Check the option for double sided then on Preset, choose Save Preset
-You have the option to rename it
-You may rename it as Double Sided
-After saving, close Textedit
Note: Whenever you open the print dialogue box, under Preset, the Double Sided Option will appear. Choose it whenever you want to print double sided.
-Open the document you wanted to print in double sided
-Click File then Print, change the Preset to Double Sided