Are you sure about this ? How can they allow multiple accounts when they don't even allow the same IP for two different persons in the same house and for that, the gambler needs to inform them prior. These details can be read at terms of Services section (https://duelbits.com/en/tos).

So this clearly means that one person cannot have more than one account at a time and even if one account is inactive, it can cause probelms anytime