On our website, we've asked users to use their real names and everyone seems to be loving it. We've noticed that the overall engagement with the site, after people began using their real name is much higher than it was before. But now, if there are two people with same names; they've to either use a dot (.) or a dash (-) or an underscore or a space to create different usernames. Is there any way to allow duplicate usernames? What problems will it create?