Not easily. There aren't any specific boxes to click on to set the print dialog to single or double sided pages, and there should be, and it's not just Numbers. The same is true in Pages and possible all other Apple apps. I spent some time on the phone with an Apple support fellow. Unfortunately, his English made him extremely difficult to understand so I found myself agreeing with him even when I hadn't a clue what he was suggesting. But together we seemed to find that clicking on Default presets and then clicking on 1 page per sheet in Layout worked. Your experience may differ. Apple should make it easier.