This is because SE's old system charged 1-month behind. I.E you Reactivated a Character on the 1st of July and it wouldn't charge you for it UNTILL 1st of august, Where as ClickNbuy charge 1-month in Advance.

so on the 1st of August you were billed by SE for July and CnB for August so 2 payments

**EDIT**: If you cause a Charge-back by requesting the fee's returned with your bank SE bans the account for good (at least its the case with credit-card charge-backs) so be carefull