> For the complete documentation index, see [llms.txt](https://docs.tryterra.co/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.tryterra.co/faq/help-topics/data-api-sdk/webhooks-dedup-and-sync-reliability/dedup-by-summary-id-overwrite-updates.md).

# How do I dedupe two payloads for the same event?

A data point is uniquely identified by the tuple `(user_id, metric/type, start_time, end_time, summary_id)`, even when `summary_id` or timestamps are null.

* When two payloads share the same `metadata.summary_id`, the later one is an **update to the same record** (providers often send an initial estimate revised as more data syncs). Treat the most recent payload as truth and overwrite earlier values.
* **Deduplicate on `metadata.summary_id`, not `start_time`** (for sleep, `summary_id` is always present). Use `metadata` `start_time` / `end_time` to determine when the record actually occurred.
* Sessions that overlap a date boundary (e.g. sleep spanning midnight) intentionally appear in queries for both days, so complete sessions are never cut off at boundaries.

See the [data models reference](https://docs.tryterra.co/reference/health-and-fitness-api/data-models) for field details.