After I played a bit more with both versions on different pictures, I would support this suggestion. Two sliders are not too complex. But in some cases help, especially on picture with forest or a lot of greens, where you don’t want to have too much texture. On those, it is easier to just pull down the slider for fine details instead of making another instance.
Still, in general, I don’t think an equalizer like module with plenty of sliders would make sense. As already written, most of the time when one level of local contrast isn’t enough, you want to target a special area, and therefore you need an extra instance anyway.