In my home office, I have a multi-function printer that does pretty much everything I typically need, except printing two sides. Here's how I get two-sided printing when I need it.
The printer is an HP CM1312nfi. It prints on the side of the paper facing up in the paper tray. The "far end" of the paper in the paper tray is the top of the page.
I print the even-numbered pages first. These are the "back side" or "left pages".
Print in reverse order.
I take the paper from the output tray, and turn it so that the blank side is up, and the top goes into the far side of the paper tray.
Then I print the odd-numbered pages. These are the "right side pages".
Print in forward order.
This only works for one copy at a time if I have an odd number of pages in the document. That's because you need one extra page when you print the second time to get the odd number of pages.
The screen shots are LibreOffice 3.4.4.