I have this same problem. Only kpdf prints duplex all the time, I have to print everything in Acroread now. It started doing this about 4-5 months ago, I think. My printer is an HP laserjet 4050N.
-- kpdf ignores duplex printing settings and forces duplex https://launchpad.net/bugs/54154 -- kubuntu-bugs mailing list kubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/kubuntu-bugs
