Payment Ammount Incorrect/semi Duplicate Order

We had this a couple of times now, and today again.

We receive a message from the payment provider an order with the ammount of € 585.19 and 11 products.
We didn't got a order e-mail (which we always get)

In the backend when opening that order it only displays an ammount of € 262.40 and 2 products.

The logs show us the following (sorted bij time. from start to later)

Orders (create)
Order: # 22612

Orders (status change)
Order: # 22612
Status: Incompleet -> Open

Orders (delete)
Order: # 22612

Orders (status change)
Order: # 22612
Status: Open -> Incompleet

Orders (create)
Order: # 22612

Orders (delete)
Order: # 22612

Orders (create)
Order: # 22612

Orders (status change)
Order: # 22612
Status: Incompleet -> Open

When checking the payment provider there are two transactions. Both have the same shopping cart number, but diffrent transaction numbers. One is paid and one was cancelled.

Reading this makes me think this customer has two browser tabs open. Tab 1 is the cart and has all the products in. Tab 2 is initially the same car but then everything in that cart is being deleted..
Customer starts adding new products in that second browser tab. Swaps back to first browser tab (still with all items in it) and checks-out that cart.

It must be something like this, however, i think this shouldn't be possible at all.

Anyone any ideas about this?