In that case, put the negative emulsion down first (actually put them with the curly side up, which mostly is the shiny side) , then put the glass on top with the AN side facing down, and try to use only the thickest films, because most films will drop slightly in the middle creating uneven sharpness. I scanned for some time using the regular holder with a slice of AN glass on top, but when I started scanning Acros, I saw immediately I wasn't getting sharp scans. I'm afraid not getting the Nikon double glass holder is a disservice to the quality of your MF cameras.