Suppose you have a stack of face-up records you have to process. Earliest on the bottom, latest on the top. Unless the process for issuing certificates/certifications requires you to issue numbers based on the date, it’s understandable (to me) that an earlier date could have a later number.
Another way I view this same info is that a form was filled out and submitted after the birth of the twins. Someone on an earlier thread suggested that, given that articles exist claiming Barack was born in both hospitals, Barack’s mother submitted a form days after Barack’s birthwhich was in _neither_ hospital.
The BCs are issued from the health dept. The submission requesting a BC for a child not born in a hospital or in another country or state is submitted to the health department, also. They would generate different documents, but they would be handled as a pile to be processed.