If there exists no prior reason to believe that two samples are truly of the same age, and even if their ages are statistically indistinguishable, they are as likely to be as far apart in true age as the measured difference between them as they are to be of the same age.
When there's no evidence suggesting that two samples share the same age, and their ages appear similar statistically, these samples are equally likely to be significantly different in actual age than they are to be of the same age.