It's interesting that this standardization effort hasn't happened earlier, because it seems such an obvious feature addition to POST requests. HTTP is decades o

It's interesting that this standardization effort hasn't happened earlier, because it seems such an obvious feature addition to POST requests. HTTP is decades old after all, and nobody thought about this prior to the payment processors? I guess nobody really cares if you have two posts in a forum with the same content, but if you do two payments it's way worse. After all, double spend prevention is what bitcoin does its hugely expensive proof of work for.