Does your PPD file (/etc/cups/ppd/<queue name>.ppd contain a Duplex option (search it for the word "Duplex")? If not, set up your printer with the PPD to which I have posted a link in my previous posting.
-- unable to print duplex on Brother HL-5150D printer https://launchpad.net/bugs/21306 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs