Definition
Event deduplication is how an ad platform recognizes that a browser event and a server event describe the same action, so the conversion is counted once.
In practice
Meta matches the event name and an event_id sent by both sources within a time window of 48 hours. TikTok and LinkedIn use the same idea with their own event ID fields.
The event ID has to be generated once per conversion, usually in the data layer, and reused by the pixel and the server event. Generating separate IDs in the browser and on the server is the most common mistake.
Without deduplication, running a pixel and a server API together inflates conversion counts and misleads bidding.
Learn more: Meta Conversions API setup.
Related terms
- Conversions API (CAPI)The Conversions API (CAPI) is Meta’s server-to-server way to send website and offline events, such as Purchase or Lead, directly from your server to Meta.
- Data layerA data layer is a JavaScript array, usually window.dataLayer, that a website uses to pass structured event and page data to Google Tag Manager.
- Event Match QualityEvent Match Quality (EMQ) is a score from 0 to 10 that Meta gives each event, showing how well its customer information can be matched to people on Meta.
How Markitech helps
Markitech connects your AI to Google Ads, GA4, Google Tag Manager, Meta and 12 more platforms, so it can check how Event deduplication is set up in your own accounts and tags and propose fixes. Every change is held until you approve it.