I'm a C&O guy and I also always thought that was a strange name: C&O Enchantment Blue and Federal Yellow, starting with the Pere Marquette. After the C&O/B&O "merger" of '63 they were officially painted the C&O colors, but as others have said, there could be variations based on the shop doing the work or the paint they had on hand. Of course photo colors can be deceiving too and prototype paint faded and weathered.
I was searching this topic because tru-color has both Enchantment Blue (TCP-292) and C&O/B&O Blue (TCP-072) in their line, I don't know why and they are a bit different. Enchantment Blue looks correct, the C&O/B&O Blue is quite a bit brighter. Same with C&O Passenger Car Yellow (TCP-275) and C&O/B&O Yellow (TCP-071), which look pretty similar. As far as I know, other than the really early Venetian Yellow, everything should be Federal Yellow.