To answer the OP , my answer would be yes , however it is very hard to prove it . It is common practice and pretty normal for casinos using the same software provider to keep and share information about players . Users could be getting their account "flagged" for example . It`s a good thing in a way as they will know that an user might be a bonus abuser , cheat or whatever . On the other hand you might be flagged as beeing a "whale" . So they could know your tendencies , betting patterns , how much you would be able to deposit , what are your limits , how often do you chase bonuses and could use that kind of information against you . What they actually do with that information ? well i don`t know , i guess it`s up to them . However most of the online casinos out there don`t need to share / buy / that information .
Let me give you an example :
Some casinos use tracking software . Once you opened your browser and went to their homepage they already know alot about you. Some information that you might be giving :
1. date, the country flag for your country , your city , ip adress ,etc .
2. the browser that you are using .
3. your operating system and other info like such .
4. the search engine used ( if any ) and maybe the search term (Query) the you used to get there .
5. Referrers - shows where visitors were prior to coming to the site. The addresses can be links and (in some cases) may be clicked on to go backwards to the site the visitors were on prior to coming to the website. You have no ideea how valuable that piece of information is..
Imagine that a casino staff member could see what you saw prior to clicking the link that brought you to their casino website .
And most important imo , some advanced tracking software have the ability to gather info about your computer and it`s vulnerabilities , like not beeing behind a firewall , lack of malware removal software and much more . So im not saying that they are doing it , but some rogue casinos could install keyloggers , trojans and other crap on your system without you having the sligthest idea about it .
Alot of you maybe wondered how in the name of God you are getting spam emails with roguish casinos on a new email account that you are not using for gambling , have never registered an account at an online casino using that email and also never registered at any suspect gambling forum using that email adress . Well go figure ...
Don`t get me wrong here ... what they do with that information is their business and i cannot prove they do shady things with it .
My best advice would be not to visit rogue casinos / casinos that you have no knowledge of , and don`t register an account before you find out more about a certain casino website / software , because you are also giving away all your personal information .
I hope my post helps in some twisted way ...