Normal
This isn’t normal and I think it’s got a lot to do with the husbandry before you got them. Don‘t give up. I am in the UK so I don’t know what Petco are like. Our large pet companies don’t sell spiders so I can only get them from small breeder businesses. I did pick up one rescue from a reptile shop, I am nervously waiting for her to moult. I am so sorry this has happened twice. Heartbreaking. I have lost 2 Tarantulas in a moult or just after, one was very young but not like this. Poor nutrition before you got them? I hope your other spiders are ok.