Like Gamstop also advise on their site behind same provided link:
It's not casino who have access to all Gamstop excluded player information but casino send certain details to Gamstop and if there are enough matches, players login will be prevented. There is no any way that casinos themselves could make it more strict, for example that name and DOB would give positive result, it's fully maintained by Gamstop who have clear criteria how many matches in details need to match to give positive answer for request and prevent login.
Many casinos have their own systems which check self-exclusion done through their license (which they naturally have access as these are their customers who have given these details, Gamstop can't share their registered player details with all casinos but they complete these checks behalf of casinos on every login or registration from UK player), these casinos in theory could make to match even if first letter of surname is excluded (which of course wouldn't make any sense but just to try make it clear that casinos own self-exclusion and Gamstop are two very different things and you can't really compare them or blame casinos software when Gamstop fails to recognize player).
As you see, they themselves speak about Gamstop may not be able to spot inaccuracies or differences, the check is completed by them, not by casinos (casinos just send player details on every login or registration and Gamstop give one of their three replies and based on that, casino let or block player). If only your name and DOB match and other details not, Gamstop don't block you and there really is nothing casino could do to recognize that player is in Gamstop.
System could be much better but now it's very clear that which details are used to recognize player and how many need to match that Gamstop recognize you, if there are not enough of them, casino just can't anyhow recognize such player (unless player has been previously their customer and casino holds all information, then often player will be spotted with less matching details than Gamstop does).
GAMSTOP may not be able to spot inaccuracies or other differences in account details, and we may not be able to prevent you accessing accounts you have created using, for example, email addresses that you have not provided to us as part of the registration process. GAMSTOP will operate on the basis of the information you have provided at registration and we will not be responsible for failure to spot errors made on your part.
It's not casino who have access to all Gamstop excluded player information but casino send certain details to Gamstop and if there are enough matches, players login will be prevented. There is no any way that casinos themselves could make it more strict, for example that name and DOB would give positive result, it's fully maintained by Gamstop who have clear criteria how many matches in details need to match to give positive answer for request and prevent login.
Many casinos have their own systems which check self-exclusion done through their license (which they naturally have access as these are their customers who have given these details, Gamstop can't share their registered player details with all casinos but they complete these checks behalf of casinos on every login or registration from UK player), these casinos in theory could make to match even if first letter of surname is excluded (which of course wouldn't make any sense but just to try make it clear that casinos own self-exclusion and Gamstop are two very different things and you can't really compare them or blame casinos software when Gamstop fails to recognize player).
As you see, they themselves speak about Gamstop may not be able to spot inaccuracies or differences, the check is completed by them, not by casinos (casinos just send player details on every login or registration and Gamstop give one of their three replies and based on that, casino let or block player). If only your name and DOB match and other details not, Gamstop don't block you and there really is nothing casino could do to recognize that player is in Gamstop.
System could be much better but now it's very clear that which details are used to recognize player and how many need to match that Gamstop recognize you, if there are not enough of them, casino just can't anyhow recognize such player (unless player has been previously their customer and casino holds all information, then often player will be spotted with less matching details than Gamstop does).