Now that our chickens are laying, is it possible for the same hen to lay both white and brown eggs?

I read somewhere that you look at the color of their "ears" to determine if they will lay brown or white eggs. Well we have 3 white hens, a brown hen, and a black & white rooster. Our brown hen seems to be the only one laying so far, (They're only 4 mo old and we just got our first 5 eggs in the last 2 days.) The brown hen has "red" ears and the rest have "white" I guess. The first egg we found was brown, and it was in the garage. The next 2 eggs were RIGHT next to each other in one of the nests in the coop - like touching - but one was brown and one white. I figured we have 2 hens laying and they both laid in the same nest. Well we went to look today and saw the brown one sitting in her nest, and later we came back to find another pair of eggs, one brown, one white, right next to each other in that nest. Is it possible our "Henny Penny" (the brown one) is laying both brown AND white eggs?