If you mean printing on both side of the sheet, then this a function of the printer and print driver.
Within OO.o, you can have a two-page document print on one sheet of paper. One page on one side of the paper and the other page on the other side of the paper. The printer is the device that turns the sheet so it can print on the other side.
Within OO.o, this option is chosen when the print dialog comes up and your operating system print driver provides (to the OO.o print dialog) all your duplex (double-sided printing) options.
--- looking at your question a different way ---
If you mean printing two or more pages on one side of the sheet, then this is an OO.o function as well as a print driver function. Some print drivers may or may not have this option.
Within OO.o, this option is chosen when the print dialog comes up either under the "Page Layout" tab or under the "General" tab and your operating system print driver also might provide this capability.
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