Verified referrals and ip verification

Hello, could you tell me, what is the advantage of a referral being verified, and what actions make it a verified member?
I would also like to know if I can verify if someone has installed the browser more than once, to know if this account as a referral and receive reward for it?
How can I assure that

@earaya let me know if it still unclear https://support.brave.com/hc/en-us/articles/360025284131-What-do-the-referral-metrics-on-my-dashboard-mean-