[kgwxd]

> If you see a duplicate idempotency key

I'm no expert but an "idempotency key" already has some major smell to it.

[yencabulator]

Then learn from the experts, maybe? https://docs.stripe.com/api/idempotent_requests

[bcrosby95]

Why? I've used plenty of systems that have an idempotency key. E.g. many payment processors will take an order id and won't let you charge an order id more than once. That's just an idempotency key by another name.