Unsupported characters in member name

you'll have to manually pick them new user names.. there's not an easy way

So what's the regex to not let more users register with similar names and what I can change in the user url to show their profile?

Even if I change the user profile to show their name and number will work? For example: domain.comm/member/***1245/ (which *** is the username of member)

You would have to go through and manually fix existing names, asking the users what name they would like.

I use this for mine: ^[A-Z0-9.]+$

That only allows numbers, letters, and periods. No spaces, underscores, special characters, etc.