Sonny Bupp (born Moyer MacClaren Bupp, January 10, 1928 – November 1, 2007) was an American child film actor and businessman. His most notable film was "Citizen Kane" (1941), in which he appears as Junior, Charles Foster Kane III, the eight-year-old son of Charles Foster Kane and his first wife, Emily. Bupp was the last surviving credited member of the "Citizen Kane" cast at his death.
Can we infer the following?
Sonny Bupp shouldn't have changed his birthname. 

Select from:
(1). Yes
(2). It's impossible to say
(3). No
The answer is:
(2).