A mid-size manufacturer ordered a batch of raw material. The request was approved in an email thread. The vendor sent the invoice twice, once by email and once with the delivery. Two people in accounts each saw one copy, found the approval in their inbox, and paid it.
Nobody did anything wrong by the process they had. The process simply had no single record of what was ordered, what arrived, and what had already been paid.
The fix was not more care. It was a system where the order, the receipt and the invoice sit side by side, and nothing is paid until they agree.
That is what Ipcosys does. Requests are raised in one place and approved by rule. Orders go to verified vendors. Receipts are recorded against the order. Invoices are read, compared line by line, and either released to payment or held for a person to decide, with the difference already worked out.