If you look at the original Moto Guzzi sales literature you will see that the valve covers on RM, Rosso Corsa, and Nero Corsa are a lighter shade of red (approaching orange) then the most common red on the frame plates.
When I got my Nero, they had both been painted to match the Nero Corsa script on the tail. But I replaced them with a candy-apple red powder coat set, which is close to the original metallic red but give it a bit more depth and character. And to my eye, is a nicer fit with the Nero. Also note, the angle/lighting makes the parts look different colors, but they are the same (so is the alternator cover).