use of names/name change

The name on my father's birth certificate differs from the name he uses.
Basically, it is like this: he is John Richard Doe Jr. on his birth
certificate but he has used the name Richard John Doe his entire life. His
driver's license, social security card, mortage, everything uses the name
Richard John Doe. The only thing in the John Richard Doe Jr. name is his
birth certificate and one life insurance policy. Is it necessary for him to
have his name legally changed to Richard John Doe or can he just have the
name on the insurance policy changed to match the name he uses?

He can do it either way but he made need a court ruling if the names differ or he may not get his money.