Interesting image Marc. It s strange what the service use can do with single top coat paintwork, bleaching from sun, wash from hand prints, fuels and oil, heat from engine... and so on, can make impressions of multi color camouflage. So even if we have single coat coat it could look as the more coat is on.
It is nice to continue in this way, maybe some findings could be find. I will search my hard drive, I think that I have download image of late war Bf109 with single top coat (but due to mess in files I can not promise anything).
Cheers