To further elaborate on the inaccuracy of the color reproduction of scanners in general, here’s an example, where I scanned a calibrated color source.

Original:

Raw scan:

As can be seen the color reproduction is pretty inaccurate. Next I do a curves adjustment (using the color matching tool) to match the gray values at the top:

While the gray values match, the color reproduction is still not accurate, and in some cases worse. So, a curves adjustment is not going to work to retrieve the original colors, and makes perfectly clear why comparing colors in an uncalibrated scan makes little sense, even if the frames have been scanned simultaneously, as browns can come out looking more red, teal can look more green, orange more yellow, etc. The solution is to create a LUT using the color matching tool to match the colors:

This way you ensure hues, contrast, and saturation match the source.