Definition
Event deduplication prevents counting the same conversion twice when you send events from multiple sources (browser + server).
Example
A purchase event is sent from the pixel and the server with the same event ID, so the platform counts it once.
How to use it
- Use a shared event ID across sources.
- Test deduplication on real checkouts and real lead forms after releases.
- Align event values and currencies so deduped events match exactly.
- Track dedupe rate so you can spot double-counting early.
Common mistakes
- Assuming the platform dedupes without consistent event IDs.
- Using different timestamps or values across sources for the same event.
- Letting multiple tags fire the same event with different IDs.
Measured as
Measure Event Deduplication with a fixed attribution window, conversion event, and spend basis before comparing campaigns or creative tests.
Misused when
- Assuming the platform dedupes without consistent event IDs.
- Using different timestamps or values across sources for the same event.
- Letting multiple tags fire the same event with different IDs.
Operator takeaway
- Use a shared event ID across sources.
- Test deduplication on real checkouts and real lead forms after releases.
- Align event values and currencies so deduped events match exactly.
- Use Event Deduplication only inside a stable attribution rule, conversion definition, and time window so campaign comparisons stay honest.
- If performance changes, check whether the metric moved for a real business reason or because the measurement setup changed underneath you.
Next decision
- Read UTM + GA4 attribution: practical tracking for paid ads (without lying to yourself) if the decision depends on interpretation, policy, or trade-offs beyond the raw formula.
- Decide which report owns Event Deduplication before comparing campaigns, channels, or creative tests.
Where to use this on MetricKit
Guides
- UTM + GA4 attribution: practical tracking for paid ads (without lying to yourself): A practical guide to UTMs and GA4: consistent source/medium/campaign tagging, conversion deduplication, and common attribution traps.