If turbotax asked for my account and routing number to pay California tax due 191 and also asked me to mail in a voucher with payment am I paying twice? my you and check

are you sure they didn't ask for the bank info to pay the TurboTax fees for preparing the state return?

If you paid your 2018 balance due by Direct Debit, you would not need to also mail a payment voucher. What is the form name/number on the voucher? I'm wondering if it's an Estimated Tax voucher for 2019.