to a degree, yea...i mean, you don't HAVE to change amps, or guitars, or anything else
i really don't understand why this and the quad-tracking thread are getting so drawn out
if you have 1 take on each side, your shit is double-tracked...if there's 2 takes per, then it's quad-tracked, and any changes in player/guitar/amp/settings/cab/whatever are merely there to get differentiate the 2 sides
personally, i like to keep everything equal on both sides for rythym tracks, at least when doubling...if quad tracking, then the 2nd take on each side might be different from the 1st, but is the same as on the other side