The difference between one and two books lies in the prestige of the school, the strength of teachers and so on. Traditionally, the last book is considered to be better, but it will not be reflected in the diploma.
There are two kinds of undergraduate diplomas:
One is the general diploma, which is issued to graduates who have not obtained a bachelor's degree; The other is a certificate that combines a diploma with a bachelor's degree and is issued to graduates who have obtained a bachelor's degree. The latter also marks the academic level of the educated.
Baidu encyclopedia-graduation certificate