Accounts Payable ACH payment amount shows double the invoice amount

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I went to process an ACH payment for a vendor invoice & it had a line that showed double the amount of the invoice. The total line was ok but when I got further in the process it said the daily transaction register was out of balance. The vendor inquiry screen shows the invoice as paid for the correct amount but under the checks tab it shows double the amount was paid. I did generate the ACH file but did not upload it to our bank for actual payment. I also tried to go in the manual check to reverse the payment but again it says it is out of balance & won't recall the invoice. What can I do to fix this? I don't even know why it happened.