If several copies are requested, and the box is checked, the pages are assembled before printing the next exemplar. Otherwise, each page is repeated. For instance, for the printing of two copies of three pages :
if this box is checked, the page order will be 1, 2, 3, 1, 2, 3
if this box is not checked, the page order will be 1, 1, 2, 2, 3, 3