You have 2x applications that are displaying the volume change. I had the same issue when I installed a "Trust" keyboard and mouse set. Windows Media Centre is displaying the volume in the middle of the screen, and I found that the Trust software I installed, did exactly the same and put a 2nd volume display on screen. Either find out the name of the application that your keyboard is using and terminate it in task manager, then adjust the volume to see if you only get one volume display. If you do and you can live without the extra functionality the software gives you then remove it. 9 times out of 10 these applications only give you access to things like shortcut keys, or some other extra feature, but most work without you having to install specific drivers.
