It's fair enough to say that a casino shouldn't allow it in the first place and the accounts should be blocked immediately when the gambler creates two or multiple accounts, but why does a gambler have multiple accounts in the first place? If you have multiple accounts, and you hit a big win with one of them, and then the casino investigates and finds out what you have been doing, they have all the rights to ban you or confiscate the funds.
I do agree. It may be written in TOS or just be seen as a fraud and treated as such. Nothing personal for the one who did such things
That's the kind of advantage the casino has—being ignorant can lead to regret. Why would they bother to close an account or investigate it when they can do that once someone hits a big win, lol. Sometimes we complain about things, but it's actually our fault. Although it may seem unethical, they don't violate any law, so they have a clear conscience.