Duplicated Entries weeks apart

So reviewing some form entries on our site we can see that we have a duplicate form submission from one of our forms but weirdly the two entry dates are from:

23rd May 2020 at 2:42 pm
6th June 2020 at 10:23 pm

The rest of the data in the entries is exactly the same (other than the “key” field).

The client phoned the user after the first submission and made a sale of a product they enquired about.

After after second submission came through, a different client user phoned the customer and talked to him letting him know the product he enquired about had been reduced by ￡1000.

The customer informed the client he had not submitted the form again but now was rather upset that they had to pay the extra amount rather than this “new reduced” price.

Obviously this means that the customer was refunded ￡1000 which now means our client isn’t very happy they’ve lost out on that money. Just because the form decided to submit itself again but a lot later.

Apparently duplicate submissions going into the DB 2/3 weeks after the original is quite a common occurrence for this client.

Any ideas what this could be?

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