POST /v1/kennet/twins and POST /v1/kennet/batches accept an Idempotency-Key header: a unique string of 1 to 255 printable ASCII characters, such as a UUID. Retrying with the same key returns the original twin or batch instead of creating another.
The same request means, for a twin, the same file name, file bytes,
end_user and confidential list; for a batch, the same requests (each custom_id, file_id and end_user, in order) and confidential list.
A request that returns an error releases its key. Keys expire after 24 hours and are scoped to an organization and mode.