The original driver that I had was "MX330 series Printer Driver Ver. 10.16.0.0", for Mac OS X CUPS. Canon support said this was the wrong one for my OS and had me delete those files and download "MX330 series Printer Driver Ver. 7.15.0", for Mac OS X. In both cases neither has the "Duplex Printing & Margin" option, though there is a Margin drop down. But "Layout" is where I have the grayed out "two-sided" option.
I also, deleted & installed the scanner driver, MX330 series Scanner Driver Ver. 14.9.0