Event Deduplication
Also known as: Deduplication, Dedup
Event deduplication prevents Meta from double-counting a conversion that is reported by both the browser pixel and the Conversions API.
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What it actually means
When you run the Meta Pixel and the Conversions API together — the recommended setup — a single conversion can be reported twice, once from the browser and once from your server. Event deduplication uses a shared event ID (and supporting parameters) to recognize that both reports describe the same action and count it only once. Without it, your dashboard inflates conversions, distorts cost-per-result metrics, and confuses the optimization algorithm. Setting up deduplication correctly is the technical key to running redundant tracking safely, capturing more events through CAPI without paying for the inflation that double-counting would otherwise cause.
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If you've added CAPI on top of your pixel, deduplication is the step that keeps your lead count honest — otherwise every form fill might show up as two.
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Related terms
The Conversions API sends conversion events to Meta directly from your server, supplementing the browser pixel for more complete and reliable tracking.
The Meta Pixel is a snippet of code on your website that tracks visitor actions and sends them back to Meta for measurement and ad optimization.
A standard event is a predefined action the Meta Pixel can track, such as Lead, Purchase, AddToCart, or CompleteRegistration.
A conversion is a completed action you've defined as valuable — a purchase, form submission, call, or booking — tracked back to your marketing.
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