UCI admits into the University first and then into the major. By picking highly selective majors, they could end up in Undeclared if not admitted into either preferred majors.
My student is fine with undeclared she has other options CS related which are not capped
But only got to know later
Glad to know they might still admit you if both major choices are not offered to you
Just be aware of the requirements needed to switch or declare majors later on. Some schools make it very difficult to impossible to change into a CS major if not directly admitted.