Makes it harder when they're all the same age doesn't it? I had no doubt my first egg was from my BO, since she was a month older than the next and the only one with red comb/wattles at the time. The other BO was the next to start and again, there was no doubt when she started. My three younger girls (RIR, Star, BR) are all the same age and maturing at the same rate so when they start, I will have a much harder time figuring out whose egg is whose.
From your siggie line, I'd say your egg is not from your EE but the egg looks just like the eggs I'm getting from my BO's so that is a possibility.