Right, even Binance doesn’t allow to use multiple account at the same time from the same ip. So there are no way to think they will be tolerate if who using fake information. Undoubtedly for that Binance will go to restrict for such users accounts due to violating their rules and regulation. I think who have make sense then will never use false things in KYC.
People can request for sub account if they meet the requirement, I have not bothered about this before though. But I have not noticed on binance that two accounts with one ID verification can not be verified, but this will not even make any sense, better to go for sub account which binance made difficult other than many other exchanges that you can open sub account easily. Using false KYC will be highly inappropriate but the OP is not talking about using fake KYC but some people can go to the extent of using fake KYC and this will lead to freezing of account if known.
Right, it sound is ridiculous like two accounts will be verify by one identity, there are no exchanges will be allow that's pretty sure. And it might be difficult to audit for the exchanges i think. Personally i don’t agree for sub account in Binance or others exchanges. Even i can't imagine to using something fake on KYC verification, Where the account is most likely to be suspended.
Why are you talking of a sub-account? I don't think it's possible when there's a KYC requirement, one account is for one KYC, even in the bank, you cannot open 2 same accounts under the same name because they only required one KYC document or verification for every client.
For a gambling site that is regulated by the government, for sure there's no difference from the requirement of exchanges in terms of KYC verification.