LOL!
This really proves absolutely nothing, since if there was a name change for example, the original information and certificate would be put under court seal (as per the statue I posted earlier), and we would only see the new updated information.
Since we’re rolling bones, his maternal grandparents moved to Hawaii to be with their flake of a daughter, so another possiblity is they adopted the kid—since mom was just a kid herself and papa `flew the coop’—and American-ized his name in the adoption petition/Decree.
Ten, twenty years later Barry decides he’ll have better luck in the brave new `Great Society’ going with the old man’s handle.
All idle speculation since, as you point out, all of this would be sealed.