Well it seems easy but for me it is not. I have dublicated a clip. The use colormask, beginnin with the top clip. The the the botton clip and finally desaturate both. The outcome is not what I wanted. I must be something horrible wrong. Advice wellcomed for a dedicated amateure.
Just tested. Apply one Color Wheel effect, HSL filter, corrections. Then apply a second Color Wheel effect, HSL filter, and corrections. It works fine for me. All on one clip. Will post tutorial in a day or two.