More likely Barry Soetoro found it advantageous to be Barry Soetoro until it become more advantageous to be Barack Hussein Obamah, Jr. and never legally changed his name back to his Kenyan name.
But who knows?
Like someone posted, "The only sure thing is Obamah is hiding something!"
Obama’s parents were not married, Obama has even said so, and in Hawaii at the time he was born, the mother’s name was used for any babies born out of wedlock.