That's definitely been pecked. Keep an eye out for the egg eater. I have golf balls in our most used nest boxes and that seems to help some. Collecting eggs a few times a day is really the best way I've found to prevent eggs from being eaten. Double yolkers are pretty common, we get about 1 a week. Nothing to be concerned about, it's just because two eggs were released into the oviduct at the same time. I would advise you to periodically check vents to make sure theres no prolapse, some eggs are so big they can cause damage.
I don't have any documentation for this, but I've seen people mention in passing that double yolkers from established layers can indicate an overweight hen. Maybe it's your egg eater
Then again, I don't know if two months is considered an established hen or not.
A lot of chickens will eat an egg that is opened, say it breaks accidentally. That doesn’t make her an egg eater. It’s when she’s opening them on purpose that it’s a problem. Accidentally broken eggs is one way to get them started. An egg eater can teach other hens to open eggs. That is not a good situation at all.
I agree that egg looks pecked. Something else that can cause damage somewhat like that is a nail sticking up in the nest or maybe a hen stuck a claw through it, especially if it is thin-shelled. But with the depth of that hole, it looks pecked.
How attached are you to your individual hens? I had an egg eater once and as soon as I found out which one it was, I ate her before she could teach the others. But I mainly raise them for meat to start with so that decision was easy.
Other people will tell you of various techniques to retrain an egg eater. I haven’t done any of them so I can’t say how effective any of those are. One way that can work is to build a roll-away nest. When the hen lays the egg it rolls out of the nest into an area where the hen can’t get to it. That would not work for me since I want my broody hens to be able to hatch with the flock, but maybe you want to consider it.
The pictures are of one of the eggs that were pecked. We have found 2 this week that were all but destroyed and eaten. I may be able to get a pic of that later. We have them exclusively to lay, and technically they are my 5 and 14 year old sons chickens. I would rather not have to eat one, but it may be an option. We had extreme cold over the last week and the girls didn't go out much, so I'm hoping that they might have been bored.