The first customer by comment time on the platform gets the item. The second automatically joins the waitlist; the cockpit shows her position. If the item is released for her, she gets the message on WhatsApp.
If the first does not confirm within the reservation window (24 hours by default, editable) or cancels, the item passes automatically to the next on the list, who gets the news and the cart on WhatsApp.
In assisted mode, you see both requests in the review queue and decide. The order timeline shows the exact comment time so you can explain to anyone why she was first.
If it still does not work: if you already sent the cart to the second customer by mistake, her order stays valid; we never take back a sent cart. You can release the wrong reservation manually from the order.