Account verification: Only 1 account per person

Question

In my community, every user should only have one account.

So I need a solution to verify that the specific account is the only one the user owns

Answer 1

The most effective solution might be the use of keystroke biometrics. A person can be identified by the way the person writes a sentence.

This company provides a product which can be used to implement your requirements: http://www.psylock.com/en