I've done it when I get a payment that takes too long. I test out new lightning wallets all the time, and not all of them are very reliable. So when I try to pay an invoice, it often gets "stuck" for several minutes trying to pay without either failing or succeeding -- just "pending." When that happens I usually switch to a different wallet and try to pay the same invoice with that one. In other words, without making a mistake, I try to pay the same invoice twice. I did not consider that I can lose sats doing this but now I will take that into consideration.