Every casino has its set of rules. Once multi-account is not allowed, they will follow it. In this case, one account will be left while the other will be blocked for sure.
Casinos barely do this, and they usually block all accounts but can have different solutions for user fund. They can allow users to withdraw deposit money while confiscate won money in such multiple accounts.
Not all casinos block one and leave the other one. Once they confirm that a player has multiple accounts, they may even choose to ban both accounts and confiscate the funds. The player would have nothing to do in such cases if the casino already covers the terms in their terms and conditions page. I don't understand why a player would create multiple accounts at a casino if they have no bad intentions.
That's right as casinos have many terms against multi-accounting and they know that this action is against their casino and can help cheaters to exploit their casinos. Therefore, with terms available, they can take action against cheaters and when they do it, they often do it in a hard way with strict punishments on multi accounters.
If a plyer forget that they had an account on this casino, it could be an exception. In such case, the registration date will be very far from the first one. If I create an account on a casino, I won't forget that in a month or so.
They can proactively ask for support about any concern on possible previous accounts before registering and especially funding their new account. Without proactive support request, any action with a new account will be considered as multiple accounting that breaks ToS while terms are not friendly with users in such violation.
