Ok so looking at low-light you can see twice as far as a human in dim conditions, so with normal vision and a light spell cast in natural darkness it states, This spell causes a touched object to glow like a torch, shedding normal light in a 20-foot radius, and increasing the light level for an additional 20 feet by one step, up to normal light.
I see this as low-light seeing in 40-foot radius of normal and then another 40-foot radius in dim. What if you had dark vision(60 ft) and low-light. With a light spell active would you use the first 60 ft with dark vision and then the last 20 ft using low-light.
I guess I’m wondering if you can choose which kind of vision you are using or if one kind overrides the another kind if it can be used.
The first part is correct.
I think the darkvision bit is also true. But remember that darkvision grants no color vision. It's monochromatic.
