It is supposed to be pretty good...
Really, if you open the BW version in Photoshop (or similar software) you can use the Eyedropper Tool to check the color at different places. Then you can see that the three channels (RG

aren't exactly the same - this is not a B&W picture, it is a Duotone converted to rgb and saved as jpeg... Then go to picture mode and convert to greyscale to get a true B&W picture and see the difference (Ctrl+Z a few times). When choosing the color and adjusting it for the Duotone a calibrated monitor is handy.
You (me, I forget sometimes...) must of course choose the correct working color spaces and also check that the monitor shows the proof color output.