Mine are exactly as Speckledhen described, exactly. I have 4 Wyandottes and 4 Orpingtons. The Orpies eggs are much, much darker brown, and never any speckling whatsoever.
When I gather eggs, all through the day, I always know which hens eggs I have. They all seem to have different laying times. Anywhere from dawn to dusk. But I always know if its an Orpie or Andy (our slang for WyANDdottes) egg.