Hi, I was trying to get the answer for that on google, but did not happen to find it. I've been using HP k209a Printer for 3 years now, but on my PC (Windows 7) and everything was working perfectly. However, when I tried using it with Mac, the option of printing on both sides of paper is not available (grey). Is there any way to do it OTHER than printing odd pages first and even later...? Best!