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.
I think KYC is the trend of centralized casinos now. We have seen threads popping up stating that they are unable to withdraw until they proceed with KYC. So if we are playing in a centralized platform, we must always be ready to submit KYC especially if we win the huge amount that surpasses the threshold of no kYC withdrawal.
Congratulations on the win, this is not shocking anymore since this kind of event is just a normal thing to your gambling session. I wish your luck rub on me and make me win another 500x-1000x. It's been a while since I experienced such a thing, I almost forget when actually, lol.