Event Deduplication
Event deduplication explained — how shared event names and IDs stop one business action from being counted twice across the Pixel and server.
Updated July 22, 2026.
Event deduplication matches two records that describe the same real-world action—commonly a browser event and a server event—so the platform does not count two conversions.
Why it matters
Dual-source measurement is useful only when duplicate copies are recognized. Timing proximity is not a robust identity. Platforms typically require matching event names plus a shared event or transaction identifier.
How it works across ad platforms
| Platform or system | Current treatment |
|---|---|
| Meta | Pixel and CAPI use matching event_name and event_id for the same action. |
| Official help says deduplication is required when Pixel and Conversions API are both used. | |
| Tag and API duplicates use a shared event_id. | |
| TikTok | Pixel/API implementations must use TikTok’s current duplicate-handling fields. |
| Current CAPI use-case/schema guidance describes browser/server duplicate handling and source-specific rules. | |
| Google Ads | Transaction IDs prevent duplicate purchase conversion counting in supported workflows. |
| Microsoft Advertising | Transaction IDs support duplicate/correction behavior in current offline/CAPI workflows. |
Implementation rules
- Generate the ID from the business transaction, not page load.
- Pass exactly the same ID to both copies.
- Keep the event name consistent.
- Retry server delivery with the same ID.
- Store the ID with order/lead records.
- Monitor diagnostics for duplicate rate.
Common mistakes
- Generating a random ID independently in browser and server.
- Changing event name between sources.
- Creating a new ID on retry.
- Using a user ID as the event ID for every purchase.
- Assuming one-second proximity will deduplicate.
Minimum QA
- Trigger one action with two delivery paths.
- Find both source records.
- Confirm one counted event.
- Reload/retry and confirm no new conversion.
- Test a second legitimate action with a new ID.
Official sources
- Meta Conversions API
- Reddit Conversion Events
- Pinterest API for Conversions
- LinkedIn Conversions API
- Google Ads conversion setup
- Microsoft offline conversions
- TikTok standard events
Technically verified: July 22, 2026. This reference uses official platform sources only for platform-specific behavior. Definitions and implementation recommendations are editorial synthesis by The Ad Spend.