This is a very common people problem. I face that too with many of my clients.
But I don’t think disabling prefilling would be a popular solution with most Manager users. If anything, users are asking for more prefilling.
You probably know this already, but I have to mention that the users could generate a new receipt starting from the Customer Statement (Unpaid Invoices) report.
If that doesn’t work, there’s another idea that you might find helpful:
It’s not the same as no prefilling, but it could be a possible solution since it will start from the Customer invoices page and the user can view and freely select from the entire list of pending invoices (i.e. unpaid and overpaid)