That's why, they multi-account on the site. Sometimes, there has some unwritten rules in casino (Multi-account can be acceptable as long the user not using anymore the old account or trying to abused promotion or referral).
I would like to go first to ask support team about my previous accounts if I forgot about those ones. I don't want to have issues because I don't go first.
I read some fake scam accusations of cheaters tried to attack casino. Those cases end like they have multiple accounts, and have similar betting pattern in a same tournament, same type of sports, same ways of betting. It's very hard to see a trusted casino handles those cases against users not correctly. They know that incorrect handles are harmful for their reputation and they are always careful about their investigation and decision making.
But wait, it's not just the casinos' job to squash multi-accounting. Players, too, should step up and embrace honesty, integrity – the whole nine yards. So, the multi-accounting debate boils down to this: are you in it to win it, no holds barred, or do you want to play fair and square, respecting your fellow gamblers?