The gameboy and the color both remain different portable consoles, the color succeeded the gameboy in 1998 a decade later by having a more powerful hardware (cpu, ram, better display screen, games exclusives), it is a little as if we added the sales of the DS with the 3DS or the psp with the vita, it is cheating.
We know the gameboy is 64.42 million at the end of the 1997 fiscal year just before the release of the color. so :
11- Gameboy : 64.42 million
13- Color : 54.27 million
But what about the 3DS and New 3DS?
PS4 and PS4 Pro? XBO and XBO X?
Those are all more powerful variations of their original systems.
3DS and New 3DS are a bit more like the GB and GBC, as in they had games exclusively running on the later version, so if you go that route at least 3DS and New 3DS have to go the same way.