Actually i did accidently one time but i doubt it was reading the nands, but the nandx was hooked up.Did you boot the console in between nan reads? This would cause your nand reads to differ as well. If not then yes most likely soldering.
What NAND hardware are you using ?http://s1152.photobucket.com/albums/...3-17033359.jpg
check em out
tell me what you think
these are one of the first, it seems no matter how i solder, they will never match
besides soldering what can be an issue