Our API follows a common industry standard called idempotency. Idempotent means that no matter if you make one or multiple successive requests, you receive the same response from the server. The result is different only if the resource data on the server was updated in the meantime. It’s the same as multiplying a number by zero - the result is still zero.
GET endpoints are idempotent because they read/retrieve information without changing anything in the backend. Even if you call endpoints like GET/Offers with multiple identical requests, all responses are the same as the first one you received.
Our POST methods are not idempotent by nature. Calling the POST/Subscription endpoint more than once, with identical request bodies, creates a new record with only the IDs created on our side to differentiate. If this is not the behaviour you need, we suggest adding validation on your end to prevent duplications.