What happens if you use the same field name in a template that is already used in a parent template?

What happens if you use the same field name in a template that is already used in a parent template?
A . You will get two fields with the same name, which leads to confusion both to users and developers. It should be avoided.
B. You will get two fields with the same name, which leads to confusion both to users and developers. It should not be avoided.
C. You will get one fields with the same name, which leads to confusion both to users and developers. It should be avoided.
D. None

Answer: A