saturent, admitting to multi accounting right there.
Actually, they didn't admit anything:
However, these accounts do not belong to me. [...] Sorry but you can not link these accounts to me since we are two different people.
And, they said they both went trough KYC:
I played by myself.. and I believe you can verify all this since we both underwent KYC..
So, according to OP, one customer is cheater and one has only one account. Tricky situation for sportsbet, maybe there is rule in ToS which says "it is allowed to have only one account per household"?