Two-sided Copies vs Prints
Two sided prints are charge per page, not per printed face.
Therefore 7 pages printed double sided are charged as $0.15 x 4 pages = $0.60.
Currently, physical copies at the copier are counted per face, meaning that copying (vs printing from a computer) same print job will charge as 7 separate pages, even when printed two-sided: $0.15 x 7 copies = $1.05