What breeds do you have? I think I have a barred rock that lays eggs like that. My black star lays a brown egg with dark speckles around the pointy end of it.
I have brown sex-links, Black Langshans, and a rhode island red. I get about 4 of these eggs that you described. light / Med. brown egg with dark brown spots. (pretty)
I am not sure if this helps you out. I am new at this so. I am still not sure what I am doing !!!