PDF invoice sent to wrong customer

Hi

We have a site where orders have been placed by two separate customers at exactly the same time, one of the customers has received the PDF invoice for the other order.

This is obviously a big personal data breach so we have had to turn off automatic PDF invoicing with order emails for now, but can you help us find out why and how this has happened?

I’m sure we’ve raised this in the past but can’t find the post, as we have had this happen before, it always seems to be when orders go through at exactly the same time.

I can provide WP admin access and server logs if it helps?

Many thanks