vbulletin Registration Deny username with Caps lock

[Naijasite]

I have a lot of spam Bot registration with similar username typs with Caps lock after the first word in the username.

Example of spam username:
IKowalski
KMcClella
KDesmond

Please how can i deny registration with username with caps lock on forum registration.

First word can have Caps lock other word should be lower case.

Your assistance will be appreciated.