Huh? In the original movie, he identified himself as “Klaatu” — after he was shot and killed, but got better, he gave the name “Carpenter” when he was in the guise of just one of the local humans. (Symbolism? What symbolism?)
You’re right Klaatu did identify himself in the first movie. Some say that the “Carpenter” name and his mission to warn and possibly save humans followed by his death at the hands of humans and his coming back to life is a Hollywood suggestion of the Passion.