Do you noticed that there are many complaints recently about gambling sites blocking the accounts of some users. The user may have more than one account but maybe they do not read the terms of service before gambling. This is the ones that we heard of. There would be more than we did not know.
The first three gambling sites that I used which were local gambling sites, I did not read the terms of service. I use the same ISP to open 3 accounts for the first gambling site. I saw no problem because I lost money than win which makes me to to have a single withdrawal. Supposing that I won huge amount of money, they could have used multi accounting as an excuse not to let me withdraw the money.
It would be good for newbies and many people on this forum that are not even newbies to read the terms of service of the gambling site that they are using. Having more than one account is against the ToS of all or most of the gambling sites.
You must read the terms and conditions for gambling in detail, remembering that money entered into a gambling site will disappear by itself, every large gambling platform only limits one account, that is the applicable provisions. If there is a gambling platform that uses many sites, it can be misused by certain parties.
For beginners, it's best to focus on one account on one site, that way it will be safe, using multiple accounts on one site will be prohibited or there are newer sites that allow 1 account on one gambling site, so far I've never done anything like this, it's better. Look at the regulations that apply.