Hard Egg and Soft Egg

Just found an unexpected pair of eggs in my lay box. I assume they were from today, but they were buried deep and I decided to check because my largest female showed the signs of having thinned out around the hips, so they may have been in there since yesterday. Anywho, found two eggs, one of them firm shelled, very well shaped and white colored. The other is a little larger, also nice shape, but very soft and little dingier in color. I had just received first clutches from two other females, all appeared obvious infertile and soon molded days after. I suppose I can wait for the mold on these as well, but I'm curious why the one is super soft while the other firm, and which of the two is good if either. Input appreciated!