They do not require kyc so they should not do anything if any users violate terms by creating multi account as they cant verify who is the real owner of the account. But they will take action without saying anything. They just say you have violated terms our our service.
I do not know a casino that would tolerate the fact that someone has multi accounts. What you are saying is that breaking the rules is okay and should not be punished. After all, if someone creates several accounts, he does not do it by accident. This is to cheat on sports betting. When something like this happens, the casino has to react. The consequences obviously do not please those who create that accounts.