Well I do not think that they are too close, but you can change them any way you want and make them as "unclose" as you want. The console palette is limited to 16 colors but each of those 16 colors can be anything you want, so as you see there is really no issue here.
It will always be 16 colors (in console emulators too) because that is how console works (in all the OSes that I know of) and it is too late to change (and no real need, too). But you can always write to microsoft and ask them for it
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