I always just mix my own on the premise that if it looks right ..... it's close enough
If you take the original colour and paint a model with it most of the time it doesn't look realistic, you'll have read on here that people adjust colours to "scale them down".
as an example if you look at the model cars painted with the rattlecans of actual carpaint, they always seem to look darker and a fuller colour.
There's a difference in colours coming from the factory too, i've noticed colour differences in lines of military vehicles waiting to be deployed.
at the end of the day i dont think it matters a great deal to be honest.