to add my two pennorth, the double siding is a printer instruction, not a wordprocessor instruction if you see what i mean. Assuming that your printer has the facility, you can choose to print the same file out single or double sided, if you double side it the printer just sucks the paper back in again and prints on the blank side.
The only exception that I can see, and its a pretty silly one, would be if you are scanning in a double sided document, then you'd have to make sure that you scanned both sides of each page.