and update Software update.
On my Epson when I select cmd & p
I have to then select the Print using system dialoge
which brings up the option to select the various layouts
when selected I get another choice in which to check the box which shows 2 sided printing.
so i updated to 10.8.5, then discovered there was an additional Samsung update in App store. I installed that one as well, but it still didn't show in system Preferences. Then i deleted the printer, added it again and it still didn't work... I contacted Samsung chat support, they helped me to get the latest driver, and hooked me up with Smart Panel. Smart panel seems useless though, as it doesn't really allow me to do anything special. It's just a small box that indicates the toner level. Nothing to add about software, or double sided printing. 'm kinda lost by now...