Turns out that there is indeed an option for two sided printing within Word for Mac, but it’s in an odd place. I believe it’s because Word has far more complicated printing options for documents, but be that as it may, it’s quite odd that you can’t choose duplex / 2-sided from within the Word print settings window. You’re definitely not the first Mac user to notice that Microsoft dropped a different printer driver interface into Word than it has in its other Mac programs.