ET-2760 Occasionally Takes Two Sheets When Double-Sided Printing

Hello!
My ET-2760 takes multiple sheets when double-sided printing, but it only seems to be with certain pages (page contents, maybe? not sure.) and I would prefer not to babysit this thing with every sheet it prints. I've tried choosing the specific paper size, and that did not work for me. I moved the printer upstairs, maybe that caused something?