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Does your “friend” bet on same matches as yours but on opposite side? Because there’s no problem if you both on same matches on same exact pick. But if you’re always have a contradicting bet then this will surely raise a suspicion for arbitrage betting which is not allowed in the casino because you can freely get rakeback and other passive reward such as airdrop and lvl up reward without losing anything.
But at least you should recover your initial deposit unless the other account successfully manage to withdraw the balance which cover your initial deposit. This story of yours about multiple account that involves family, friends and other relatives is the common reason of those players caught doin arbitrage bet and different kind of abuse.
No, my friend never even bet on any same game, he is not even playing on Shuffle anymore. Also myself I did not do arbitrage at all.
All I did was play casino games (what can be wrong about that, it's even dumb to play those games in the long run but I liked it just for fun) and some NBA sports bets. I guess they did not like that I won more than I lost. And therefore they conveniently assume I must be the same person as my friend. To confiscate my winnings is extremely rough and very doubtful act, but to even confiscate my deposit it simply theft.