What happens when invoices get paid more than once? Until today I thought, that lightning invoices can only be paid once. Where do the funds go when an invoice is paid more than once? Will every payment reach the destination node or can reusage be detected and nodes within the route can keep the funds?
Edit: The same invoice is paid with different wallets and the users get confirmation.
It is possible that intermediate nodes on the route between you and the payee may track previous payments they have forwarded. If this happens, then the first time the payment_preimage for a payment_hash is revealed, any node along the route could remember it, and if they see the same payment_hash used again in another payment, they would be able to respond with the corresponding payment_preimage before forwarding the payment along the route, and this would allow them to claim the funds which are being spent without the intended recipient ever receiving them.