but for my time here never came across any exchange issues that relates to double.
Do you think gambling sites should be allowing double account?
Of course they wouldn't mind if their users chooses to create a multiple account or not as long as those account is always active they're perfectly okay. But one thing you should know is that there are some gambling site that you can't create a multiple account using one phone number/email.
I guess is actually the same to every other betting site, you can only do that by using different phone number and as well different username, at this point it will be very difficult for them to figure out. But if you make it very obvious to them by using a particular phone number or username to create a multiple account, definitely they won't allow you to do such.