My alarm provider took a double deduction this month because, per their text the day before, new rules meant that DDs should be only for services about to be supplied and not deducted for arrears.
As per RedOnion and you are within your SEPA rights to apply to your bank for both DDs to be refunded. Advise your supplier to check with their bank/SEPA about *any*new rules governing these payments. I'm not aware of recent changes.