Sorry for the late response, and thanks for trying to help. Problem still isn't solved though. I tried downloading and installing a "ppd" file from the RICOH website, and re-added the printer, but it's still using a generic post script driver, and I still can't do duplex.
I've looked through every menu option (layout, color matching, paper handling, paper feed, cover page, scheduler), and there's nothing that allows duplex printing. In the layout menu, it looks like there's a 2-sided option bar, but it's unselectable.
I looked under "options and supplies" in the system preferences as you suggested, but there's no option to allow duplex. Perhaps this is because it's using the generic driver, but I'm not sure how to get it to see the ppd thing I downloaded (I grew up on PC's and I'm still a bit of a Mac noob).
Thanks