How to Troubleshoot Meta CAPI Deduplication Issues

When both the Meta Pixel and Conversions API report the same event, Meta can double-count it. This is the most common Meta integration issue.

How Deduplication Works

Meta deduplicates based on event_name + event_id:

Pixel sends:  event_name=Purchase, event_id=order-001
CAPI sends:   event_name=Purchase, event_id=order-001
  → Meta counts: 1 event (deduplicated)

Pixel sends:  event_name=Purchase, event_id=order-001  
CAPI sends:   event_name=Purchase, event_id=order-002
  → Meta counts: 2 events (different event_ids!)

Common Causes of Duplicates

Cause	Fix
Missing event_id on CAPI events	Always include event_id
Different event_id from pixel vs CAPI	Ensure both use the same ID
Missing event_id on pixel events	Add event_id to pixel calls
Different event_name	Pixel uses “Purchase,” CAPI uses “CompletePayment” — standardize
CAPI-to-CAPI duplicates	Overlapping relay batches without consistent event_ids

For Offline-Only Events

If you’re uploading offline events (phone calls, booked jobs) that have no pixel equivalent, you only need CAPI-to-CAPI deduplication:

CAPI upload 1: event_id=job-2026-001 → ✅ Accepted
CAPI upload 2: event_id=job-2026-001 → ✅ Deduplicated (counted once)

TUOCA generates consistent event_ids for safe retries.

Checking for Duplicates

1. Go to Events Manager → your pixel → Overview
2. Compare pixel events vs server events vs total events
3. If total > (pixel + server), deduplication is failing
4. Check Diagnostics tab for deduplication warnings

How TUOCA Prevents Meta Duplicates

1. Consistent event_ids — Same record always generates the same event_id
2. No pixel overlap — Offline events only go through CAPI, no pixel firing
3. Retry safety — Re-uploading uses the same event_id = safe deduplication