That's right, I forgot about the Fujitsu and Runco
I don't care for the gray or duplicate image sidebars either. I was able to find a workaround to get black sidebars, but this may be limited to STB's that will allow this. I've shared this before and will post here again for anyone who may be able to get this to work too.
(Randy, I replied to another of your posts with this info hoping maybe this would work for you, but not sure if you saw it. I'll PM this too you too just in case.)
I don't know if your STB will allow this, but I found a workaround to get black sidebars when watching SD through my DTV HR10-250. I don't care for the gray bars or image matching bars either.
I set the HR10-250 to output letterbox color black and set the TV aspect correction to Panel which outputs 4:3 material with those black sidebars. Then on the Pio I keep my display on FULL. This way it is technically stretching that 4:3 image with the black bars out to fullscreen - otherwise with the display on 4:3 I would have the 4:3 image with black bars and gray bars.
EDIT: Randy, I just realized you own a Panny, so this may not be of any help for you to begin with...