Many companies now operate this 'rolling mandate' system, whereby they take a repeat payment, sometimes a whole year after you originally provide the direct debit mandate.
The mandate is just that - a permission for a third party to dip into your bank account whenever they like, and provided the mandate is current (most of them are) your bank will pay without any reference to you. In the main it's a safe system - you wouldn't provide a mandate in the first place if you didn't trust the other party ................would you?
Having said that, with your hand on your heart could you recite the details of every direct debit you have on your bank account? I don't think I could.