I used the color picker tool to choose colors from one file and fill it in another file. The color shows as desaturated when the other file is active. Both files are on the exact same settings, but I don't know what is happening. I reset the tools. But nothing.
Are you sure that mode (RGB, CMYK, etc) and assigned color profiles is the same on both files?
May be you turn on Proof Privew (Ctrl-Y) on one of the files.
PS. my english is poor )
Different color spaces, resulting in different numbers. And vice versa, same numbers result in different color.
Convert one of them, and they will match.