What happens to the old record if we re-parse and re-index the same candidate later?

With de-duplication enabled, the system finds the existing doc (by your chosen key) and replaces it — i.e., deletes the old indexed doc and indexes the new one. Keep a stable dedupe key (e.g., email/name/phone) and store the candidate’s unique IDs on your side. If you need a dedupe checkup, mail support@rchilli.com.