As far as I know, no.
The only reliable way of locating a duplicate account is through IPs. Different modems have different IPs, so the identity of the account he makes is already different to the original one. And this is most abused using dynamic IPs and mobile data, where the IP address shifts every time you go online.
Unless the user gives himself away, that is. Such as publicly exclaiming "I'm [insertusername]!" or maybe through less obvious ways, such as identifying his DS's FC as the banned IP user's (yeah that's also been done before).
Hope I helped!
