And also, if you ask "what should we call you," DO NOT use that as any sort of unique identifier. I just registered on a site that did not let me use my given name as "what should we call you" because it was taken. The stupidity.
If you need something unique, generate it, and keep it to yourself. I don't care a whit about your database.
It sounds like the form you filled out just poorly labelled their "Pick a Username" field; The concept of a website generating something to call you is interesting though. It could lead to hilarious scenarios.
No, the login is your email. Or is there a login and a username? Stupid again.
And no, I don't mean generating something to call me. I'm assumming they need a unique digital identifier, and they're just falling back on "name," whatever "name" means.
>> "Or is there a login and a username? Stupid again"
Lots of sites allow you to login with a username or an email address. I agree it can complicate things but is you need an email address to validate a user is real and a unique username for the service (e.g. it's social) allowing either for login will probably result in less forgotten logins.
Maybe I'm wrong, I was always under the impressions one of the main reasons to ask for an email address was to make things more difficult for bots. Rather than just setup a script to create accounts on your server they would also need a valid email address for every attempt.
My stage name is "Bill P. Godfrey". (Because Google have too many called Bill Godfrey ahead of me.)
In an informal setting I prefer to be called "Bill", 4 characters which appear nowhere in my legal name.
So yes, please have "What should we call you" field on your forms.