one of these eggs is not like the others...

So, I've collected many pink-brown eggs and many green-blue eggs. In addition to these, I've found two specked brown eggs. I know Ginger, my Auracana, is laying the green-blue ones - because that's what Auracanas (Easter Eggers) do. I know Penny, my Black Astralorp, is laying the brown-pink ones because I saw her pop one out and pretty much caught it as it ejected (!). I don't know if Penny is the one laying the occasional speckled eggs or if maybe Bertha, my light Brahma, is laying them. A mystery....