I came across this when I got a double and wondered if anyone else had spotted any other examples? I know that the same figures have been produced in different colours of plastic before paint was applied, but this is the first paint variant I've come across. I'm assuming it's a factory error due to it being missing paint, instead of a different colour or added paint.
As you can see, the figure on the left is missing yellow paint from his feet and upper thighs. He's also missing a blue rectangle on his belt and a blue triangle on his upper chest. The yellow used on both figures is also quite definitely two different shades (one "neon" the other "lemon").