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Processed vs Deduplicated

What Meta's two labels actually mean, why a "deduplicated" server event is good news, and what a healthy row looks like.

updated

“Deduplicated” is not an error. It is the system working. When Meta labels your server event deduplicated, it is telling you it already received a matching browser event with the same event ID and has collapsed the two into one conversion. That label is the closest thing Events Manager gives you to a receipt for successful pairing.

The healthy picture

One event row, showing Processed from 2 sources:

Source Label Meaning
Browser Processed This copy was counted.
Server Deduplicated This copy matched the browser one and was folded into it.

Which half gets counted and which gets deduplicated is Meta’s business, not yours. What matters is that both arrived and both carried the same ID.

Why “one source only” is not automatically bad

A common report is: only one row appears, sourced Server, and after a few seconds it changes to “deduplicated”. No browser source is ever listed.

Read that carefully. Meta cannot deduplicate an event against nothing. If the server copy is being marked deduplicated, a matching browser event reached Meta. The pairing is working; what is missing is the display of the browser half.

The usual reason is session scoping: the Test Events tab shows browser events only from the browser session that has the tab open. Watch and browse in the same profile and the second source appears. This is covered in step 3 of Events don’t show.

When it really is broken

Deduplication depends on both copies carrying the same event ID. If they differ, Meta has no way to know they are the same conversion, and you get two events instead of one — with no error anywhere, and numbers that look better than reality.

To check directly rather than infer:

  1. Network tab → the facebook.com/tr request → its eid parameter.
  2. The plugin’s log → the event ID recorded for that page load.
  3. Compare.

Dedup Doctor does this comparison for you, on every event, and shows the platform trace ID alongside each server send.

Why “deduplication is enabled” is not evidence

Every plugin in this category has a deduplication setting, and every one of them will happily report that it is switched on. A setting describes intent. The event IDs on the wire describe what happened. They are not the same claim, and only one of them can be checked.

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