How do I fix Meta deduplication between the pixel and Conversions API on Shopify?
Short answer
Meta counts a browser event and a server event as one only when both have the same event name and the same event ID. If one source sends a different ID, or a second app sends its own server events, Meta counts the purchase twice.
Why it happens
- Two server sources. Shopify’s Facebook & Instagram app and another app both sending Conversions API events.
- Mismatched event IDs. A custom pixel or tag that creates a new ID on every page load instead of reusing one per order.
- Different event names. One source sends “Purchase” and the other a custom name, so Meta can’t pair them.
How to fix it
- Read Meta’s diagnosticsEvents Manager › your dataset › Diagnostics lists deduplication problems by event.
- Find every server sourceIn Events Manager open Purchase and look at which integrations send it. More than one server source usually means two apps.
- Keep one setupUse Shopify’s Facebook & Instagram app with Maximum data sharing as the only Meta connection, and turn off Meta events in other apps.
- Test one orderPlace a test order with Test events open and confirm the browser and server events show as deduplicated.
Check it worked
After 48 hours, Diagnostics should show no deduplication warning for Purchase.
Common questions
Do I need both the pixel and Conversions API?
Meta recommends both: the server catches purchases the browser misses. They just need matching event IDs.
How long does Meta wait to deduplicate?
Meta’s documentation describes a 48-hour window for matching events with the same ID and name.
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