Here's tonight's update:
I candled the eggs, yes I candle them every night, can't help myself, I always do. I can clearly see red spots or veins starting in almost every one of the Araucana eggs. I can't see anything in the "Twin" egg. But it does appear to have an air cell at each end of the egg and there isn't really a big end and a small end.
I'm also happy that the duck eggs are fertile. Who knew? The mallards just turned four months old this week. The Rouens are five months old but I had read they don't reach maturity till much later so I'm guessing one of the Mallard drakes is the daddy. Somehow out of 17 ducks I ended up with only 5 females and 12 males. One of my females disappeared the other day so now I'm down to 4 (3 Mallards and 1 Rouen). I don't know if she flew away or also went off to nest. No sign of "fowl play" or anything - just gone. When another female disappeared two days later and I went looking for her, that's when I found her on her nest under the wooden sofa in duck house. I think she might be broody cause she was there for about two days and when she got off nest that's when I found all the eggs. I took them all and now feel bad. When I went to check today, she had made a new nest in corner, out in open and had laid another egg. I think I'll let her keep them and see how many she lays and what she does from here. I guess it goes to reason that a female duck with 12 males in the house will have fertile eggs but they must be very private cause I've never seen anything going on and I'm out there most of the day.