Google has accidents with the creation of multiple accounts. These errors should not be considered as abuse because these accounts are normally not active. The genuine dual account breach is better detected with such pieces of evidence as deposits made by the same source or identical IP. Casinos are supposed to look into real evidence rather than good faith error. Extra checking which account is attached at the time of registration can help avoid the superfluous problems.
I didn't quite understand what accidents you are referring to. What exactly do they lead to? The creation of multiple Google accounts with the same nickname? Or the creation of multiple casino accounts based on the same Google account?
If you mean multiple casino accounts, what does that look like in practice: I log in to BetFury via Google and suddenly end up in an account where my balance is empty - is that what you mean?
And what if I keep getting logged into this accidentally created account - would there be any way to withdraw funds from the original account that I no longer have access to?