What if an addon domain matches a primary domain? [SOLVED]

How’s everyone doing? Being new to web hosting I just learned about addon domains. The question I have is what happens if you create an addon domain that happens to match a primary domain somewhere? When navigating to the URL will one take priority over the other? Will cPanel prevent addon domains that match other domains?

Think I found my answer. The addon domain still needs to be registered just like a normal domain before it can be used. So if I choose google.com I could create the addon domain, but I still couldn’t use it.