Preventing duplicated payment for the same invoice ID (PayPal)

Hello,

Recently we had customers who inadvertently paid twice for the same invoice.
So we needed to refund one of the payment and assign a new subscription in the backend to make them have active subscription.

I understand that duplicated payment can possibly happen.
(I could reproduce the duplicated payment using the 'Back' button.)

However, I have a question about how you deal with invoice ID in transaction data.

Within our PayPal payment receiving preferences,
'prevent accidental payments by blocking duplicate invoice IDs' is set to
"Yes, block multiple payments per invoice ID". (screenshot attached)

So I suppose it should prevent duplicated payments for identical invoice.
But the issue is... each of the transaction record has different 'Invoice' ID in PayPlans (screenshot attached).
Actual Invoice ID is stored in item_number field instead.

Isn't it the reason why PayPal does not recognize these transactions for identical invoice?

I think you can reproduce the issue on your end.
Please let me know your opinion.


Thanks,
Rikao