I also think that perhaps the edges where the two scans end in the middle will always have some color variations. I took this thing to Easy Button copy center and they made some copies but could not give me a digital copy.
The guy also trimmed off part of the end of the orginal. I thought he was saying it would not fit and the end would not be on the copy... I did not know he meant he wanted to cut the end off
It looks like it is just slightly too big for the frame I have this in.