We recently spent some time updating our site and the integrations we have with our accounts system and this resulted in a number of emails being sent out that related to orders placed as much as a year ago.
Apologies for all who received these and were concerned that duplicate orders had been created or similar.
The issues have been resolved this end and the work carried out should ensure that order dispatch/completion notifications are only received once and allow us to get VAT invoices, and similar, out in a more timely fashion.