So I take this allegation against Sportsbet is unfounded.

It seems the OP was using the same address to send BTC to Sportsbet that was used for another account therefore was in breach of Sportsbet ToS.

In this instance it is very clear Sportsbet were well within their rights to ban the user accounts for multi-accounting even if 2 different KYC were provided simply because a single BTC address was used.

There is a high probability that Sportsbet would have kept quiet and took no action if the OP had lost funds and kept losing them but took action after he won or tried to withdraw won funds BUT there is no proof that would have happened. When a user accepts ToS for using Sportsbet or any other betting website, they play by the rules or they will be banned.

Conclusion #1: Sportsbet acted well within their ToS that the OP willing signed up to do therefore Sportsbet did nothing wrong
Conclusion #2: Never use the same IP address, never use the same device to place bets and never use the same BTC address to send/withdraw funds when using Sportsbet otherwise you will be in breach of their ToS