In Ubuntu 14.04 , default document viewer doesn't support both side printing of a PDF document.
To save paper, one must print on both side of a paper.
Here is the trick to print on both side of paper.
Right click the document and select 'Open with' option. Now select 'Google Chrome' program from the list. Document will open in a new chrome window/tab.
Press 'control + p' or select 'Print' form 'file' menu option.
You will see the 'print preview' window. On the left hand side you will see options where at the bottom you can select 'Two-sided'. Printing now will print the document on both side of paper.
