Re: How to deal with the problem that the same user pays on different tabs in Magento
On checkout, Magento will recheck cart_id according to the current user, so I think your case is not realistic. In case cart_id does not exist or was ordered by tab 1, Magento will report an error about the cart when you click on the checkout button In the case of still being able to check out, I think it has something to do with the payment module you are using.
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