Operating system: Windows-10-10.0.18362-SP0 64 Bits
Graphics card: GeForce GTX 1070/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 436.15
Broken: version: 2.82 (sub 6), branch: master, commit date: 2020-02-11 14:45, hash: rBc939b4df18e9
Short description of error
Having 2 or more inflow objects in a smoke simulation, each with its own smoke color, causes darkening and other hue color glitches, even when the two smokes don't mix. At first I thought this was maybe an intended effect, like burning smoke, but with just one flow object the smoke comes out with a proper uniform color.
Exact steps for others to reproduce the error
Open this file, select the domain and bake the smoke sim to see the darkening, you can see it better in Cycles. You can move the object "model2" out of the Flows collection and rebake again with just one Flow object, and see the color to compare
The attached images use a saturation node on the shader to exagerate the color so you guys can see it more clearly