I know just a little bit about adoption law.
Even in the very unlikely event that the DATE of birth was changed on an adoptive birth certificate, the YEAR would not. Nor would the change of date be more than a minor change; for example November 8 might be changed to November 11. It's HIGHLY unlikely that it would happen at all, but IF it did, that would be the only kind of date change at all.
If you know for certain that your son was born in November of 1982, and this young man was born in February of 1981, then he is not your son. Positively. For sure.

