I don't know where you got them, but EE's are a type of chicken, not a breed. They are simply chickens that might have the blue egg gene. They can be crossed with any chicken and, as long as they have the blue egg gene, they can be called EE's. They can look like any other chicken; color, pattern, leg color, skin color, size, different number of toes, it does not matter. Even the pea comb is not an absolute requirement. The blue egg gene follows the pea comb gene about 97% of the time, so 3% of the time, it does not. There are no rules for what an EE will look like.
It is not unusual for a black chicken to have black legs. Obviously, there are dark leg genes in that one's background. People wil say that an EE should have green legs. Mine has yellow legs and lays a beautiful green egg. There are no rules, but the eggs are very nice.