Detecting if a user has multiple accounts is not that hard even if the casino do not ask for kyc.
The problem here is that since the casino promote itself as decentralized and all you need to login is to connect your wallet then prohibiting multi-accounting doesn't really make sense!
BTW, doesn't dex mean decentralized exchange?
I have to agree on this part, prohibiting multi-acc when the only means of login is a wallet will be extremely problematic. People change their wallet from time to time. If someone gets flagged because he uses different wallet address [after emptied the first one] from the same IP, that's actually more hassle than their counterpart, the centralized casino.