BOLT 11, real time micro payments, and route redundancy

In an email exchange, Rusty Russell and Andy Schroder discuss the limitations of lightning payments. Firstly, it is not currently possible to pay the same payment request twice as this could result in someone in the middle taking the funds. Secondly, during a payment route going down, A has to wait, unsure if they'll try to redeem the offer or not. Thirdly, there are concerns over privacy with the use of refund addresses for lightning payments. While nobody along the route can see it, it still reveals the payer's identity to the payee. The need for a flag in BOLT 11 to allow D to tell A it wants a refund address was also discussed. Schroder asks how a payee distinguishes payments from different payers when using BOLT 11. In response, Russell explains that in this case 'p' is the payment-specific variable. Additionally, he clarifies that if doing key recovery is deemed a dumb idea, the n field can be used instead. Finally, Schroder suggests that newcomers should be informed of the differences between lightning and blockchain donation addresses.