I can press both of those keys at the same time on my Leopold. The kro varies from computer to computer for me. I can do 18kro on my Via EpiaM, 12kro on my Zotac IONitx, and only 6kro on my EVGA P55SLI. On my EVGA it does not matter which of the rear ports I use, they all have the same. It appears that not all usb controller are created equal then?