You might try the mysterious options at File | Options | Advanced: Print: "Print on front of sheet for duplex printing" or "Print on back of sheet for duplex printing." I think this is more of a page order issue; I have noticed that my printer,
which normally outputs pages face down, when duplexing, prints the back of the sheet first in order to output the pages back side up, which keeps the pages in order. A printer that ordinarily outputs pages face up will usually print them in reverse order for
the same reason and presumably prints the front of the page first. So I doubt that these settings would be relevant to the page orientation issue, but they might be worth a try.
Provided you aren't printing portrait on the back of landscape or vice versa (which Word will make Herculean efforts to avoid), you should at least be able to rotate the physical page after printing.