RESTful POST retry response

This question is about how to respond to retried POST requests.

Although POST doesn't have to guarantee idempotency, often we have to. For example, orders created by POSTing to an /orders resource should be able to be safely retried as the request or response can fail for many reasons (Stripe https://stripe.com/blog/idempotency recommends handling this via unique idempotency keys with each request).

Should the API respond with 201 Created with the retried requests too or should it be 200 OK? What is the recommended approach?

Returning 201 for a retried request doesn't seem correct as a preceding request may have actually created the resource and the retried one had no effect (eg. in the case of client not receiving the response when the resource was initially created which caused it to retry)

via ubi