Is the duplexer now a DOS feature?
Back in the day, if your printer didn't contain twice the RAM of any machine on your network, you were doing it wrong. Some of those postscript renders at 600dpi took up a lot of space, and more processing power always helped get through work quicker too.
Of course, the other way to DOS a printer was with an infinitely recursive PS job. Or, as the title says, turn on the duplexer which was almost guaranteed to cause a paper jam.