We highly recommend using the PUT method to prevent creation of duplicate usage records
The POST method creates new usage records and allows creation of duplicates. For example: if you submit a usage record with start_time 12:15 UTC and 12:30 UTC for the same customer, product and dimension, two usage records will be created for that hour. We do not aggregate the submitted quantities. Be aware that marketplaces don't allow the submission of duplicates by default, it's usually only allowed for special reconciliation scenarios.
Customers can be identified in two different ways: by either providing customer_id and product_id, or by providing subscription_id