I would put some Vaseline on them to help heal it up. We're they kept with turkeys? There another thing called black head that comes from turkeys. Sorry I keep thinking about other things. Here's another website that shows different pictures between pecking injuries and fowl pox...
The only other thing I forgot to say was that with 2 chickens it's hard to establish who's the boss sometimes so if they were always left alone without any other chickens then that could have been the reason why when you got them they had the marks.
I never use a thermometer to measure the temp in my brooders. The best thing is to do what you seem to be doing already. Go by what the chickens tell you. If they aren't sleeping directly under the lamp or reaching up to it they are fine. If they are too hot they will hug the farthest wall and pant.
Its kind of hard to tell because alot of chick's look so similar as babies. I would try and repost after they are fully feathered so the patterns or marking are more unique.
It's possible that the chickens are pecking each other. Maybe they are bored or trying to establish a pecking order. The only other thing I could think of would be fowl pox. The most common one is dry pox. Its appears on unfeathered parts of the chicken like comb and legs. It starts off white or...
So lately my hens have only put out about 2 eggs a day which is weird because I have 7 laying right now. Part of the issue I think is that we are merging our new pullets with our olders gals and its causing some stress. Anyways this morning I was looking under the coop which has about 9 inches...