Got an order after another shopper

So I took a very boosted order late tonight, and as I start to shop I can see one previous message from shopper which confirms someone else at least started the shop. Went okay, some of the produce was out of stock but the order was pretty small didn’t take too long. There was what looked like a replacement for some item (couldnt see original item) that was still listed in the order (now out of stock) along with an original item that was the same item as what they replaced the other with (so out of stock too). I go to deliver and the same order is sitting at this persons door. Does this mean the other shopper actually did finish the delivery? Would their past messages even show at that point if it was technically a reshop? Or, if this was customer fraud why would the groceries still be out there? It was the correct address and they selected left at door with no details so just wondering how this happens.