These days you can hardly find casino that are completely kyc free, for whatever reasons at some point you will be required to pass kyc and particularly in sensitive cases as this issue of multiple accounts it's through kyc verification that can be used to prove your originality as the account owner and to further prevent you from having such experience in the future. At this point the ball is in your court to make your decision depending on how important your account is to you.
They can have service terms that they can do special, advanced KYC for conditional situations with their user account and suspicious activities. Even if they are completely KYC free at the moment, because they are a centralized service, they have to register license (if not now, they can do it in future) and have to obey to regulations, in future they will probably request KYC on their platform.
Don't use any centralized service and think you are free from KYC completely. If you are very hardcore, dislike KYC, don't send big money to your online accounts and feel disappointed or painful later because of KYC requirement. Your account is not important but your money is and you will have to KYC even you don't like it.