Indeed, that is the standard practice as I understand it. Adoption law makes a great effort to make sure adopted children are not aware that they are adopted. If a bunch of kids all show up to play little league and they all happen to be born the same year (as would be normal if they are all in the same grade.) then an adopted child might start wondering why his birth certificate looks different from the others.
For that reason, the standard practice is to MAKE them look correct for the year of birth. I think the Obama legal team took advantage of this routine practice for adopted person's birth certificates, to get him one that *LOOKS* normal for the time period of his birth.
Thanks for that interesting info. For additional cover, HI could always say Obama has the maturity level of a kid on the playground, so they had to treat his BC as they would that of a child. ::snigger::