With dvips, you can print in duplex or tumble mode
by using the -h option:
dvips -h duplex filename.dvior
dvips -h tumble filename.dvi
The difference between duplex and tumble concerns whether pages are printed with opposite sides sharing a ``top'' of the page (duplex), so that turning the page side-to-side leaves both sides correctly oriented (as in a book), or whether these pages are flipped vertically (tumbled), so that turning the page up leaves both sides correctly oriented (as in a legal notepad). The orientation will obviosuly be somewhat different if the printout is landscape mode instead of portrait mode. For most uses, the duplex mode is the more fitting.