You said the female corn snake hasn’t been with another corn snake in 6 and a half years and that she was 8 weeks old. So that leads me to believe she was too young for the retained sperm phenomenon. It’s more likely to have laid these eggs based on the parthenogenesis effect. Always treat any egg as viable and incubate it with a high index of suspicion after you candle them. Sometimes it’s very apparent that a egg is infertile but just be extra vigilant. I’ve seen some reptiles come out of some strange and weird looking eggs. Candle everything and incubate until proven otherwise.