The fact that Obama didnt know a BC# and date filed that would work together suggests that he didnt have a valid 1961 birth certificate to copy that information from.
Would be untrue. What if Obama had that dead child's birth certificate (I do not remember her name) to work from? It is ENTIRELY possible that the dates would be messed up if he picked that certificate number, hoping not to get caught. Recording the birth would probably be out of order. It wouldn't be a priority.
He is most certainly using the BC# from somebody else. But even somebody else couldn’t have that combination so he either didn’t see the “date filed” for that other person, or he thought he’d fudge the “date filed” and nobody would notice.