At the time of the adoption of the Constitution, they were:
1) Born in the colonies..not G.B. (most if not all anyway).
2) British citizens AT birth
3) U.S. Citizens.
they needed it because the were only citizens of the U.S. who also happened to have been British citizenship at birth. Obviously, the declaration in 1776 didn't give them Natural Born status.
The Immigration Act of 1790 states (in part): "…And the children of citizens of the United States, that may be born beyond sea, or out of the limits of the United States"
Pay close look at the 5th word 'citizens' Notice that it is plural? As in, more than one? Barry's father was NEVER a U.S. citizen of any kind. This act of 1790, about 3 years after the Constitution was 'framed' further proves that Barry can NOT be a NBC. The reiterated that to be a NBC...one had to have TWO citizen parents. Not one.
At the time of becoming POTUS however....they knew that all of them were:
Both U.S. Citizens AND British at birth.
Today, Barry is Both a U.S. Citizen (alleged, not proven) and British at brith.
Therein of course lies another problem, he...Barry the politician alleges that he was born in Hawaii. However, as we all know there is no proof of that as of yet.