Could also be "Glazing Maroon" - 567G which is also a 230SL/250SL colour (which is what the car in the photo is).
I agree that "Copper" would be one of the rarest exterior colours.
Two-tone Colours are also rare and my favourite (biased here).
The Pagoda at the Mercedes museum in Stuttgart has a particularly rare and interesting combination - it looks to be Gold in colour - perhaps 'Tunis Beige'? (462H) with a Blue Roof (and hubcaps). The blue looks to be metallic. Despite its annoying flaws it's still a beautiful car. (ever seen an ugly one?).
BTW- Trust the Germans to have such beautiful colours for these cars and such boring colour names. Take my cars for example - Most people admire the colour of my car and ask about the colour - I feel somewhat embarrassed when I reply with 'Grey Blue' and 'Dark Red' (even Dunkelrot sounds deadpan.)
If only they commissioned the Italians to name the Pagoda colours we would have "Grigio Azzurro" and "Rosso Scurro". .....Think of how many cars they would sell if an Attractive Saleswoman described those cars to you back in the swinging 60's!
................sorry I digress