Event ID deduplication is the pattern where the same conversion event fires from both the browser (client-side pixel) and the server (CAPI). Both events carry an identical event_id. The ad platform receives both, sees the matching ID, and counts the event once. This is the standard pattern for redundant tracking against ad-blockers and iOS restrictions — you get whichever signal arrives first.
Event ID deduplication
The pattern of sending the same conversion event from both browser and server with a shared ID, letting the platform deduplicate.