For ordinary perfect-bound books, a single page is enough to output, but the facing pages are thread-bound. Thread-binding is expensive and troublesome. There is no obvious difference in printing.
It is best to make a small folding hand for the opposite page (that is, use a few pieces of paper to cut it into small pieces, stack it and mark the page number). Some of the ones on the Internet are not very accurate, so This is the best way.