This requires colluding with a miner, since nodes will reject a transaction that spends the same output as a transaction they've already seen. For a small payme

This requires colluding with a miner, since nodes will reject a transaction that spends the same output as a transaction they've already seen. For a small payment like a coffee, it should be enough to check that the transaction has a reasonable fee and wait 1 second to see that it has propagated through the network.