Account showing I have a Comcast.net email

Hello,

I recently activated service for my Xfinity WiFi/gateway. When I go to log in to certain pages, my login ID shows my email as Comcast.net instead of my actual iCloud.com. And I am seeing two different email addresses tied to my account, one my actual email, and the other the Comcast.net one. From what I can tell, I can't even access this email anymore as the service has been fazed out. Is there some reason I have this additional email tied to my account?

Thanks very much.