I was always under the assumption that v40.63 was the single chip version for the a 500/600/2000 and 40.68 was the 2 chip version for the 1200/3000/4000.
I have v40.68 in may A1200T, but I use v40.63 in UAE (I downloaded a priate one off the interweb because I was too lazy to figure out how to grab the roms)
