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.
Why this matters
This term matters because it affects how you interpret performance and make budget decisions. If you use inconsistent definitions or windows, ROAS/CPA can look "better" while profit gets worse.
Practical checklist
- Write a 1-line definition for "Event Deduplication" that your team will use consistently.
- Keep the time window consistent (weekly/monthly/quarterly) when comparing trends.
- Segment results (channel/plan/cohort) before drawing big conclusions from blended averages.
- Sanity-check with a related calculator from the same category on MetricKit.
- Read the related guide (e.g., UTM + GA4 attribution: practical tracking for paid ads (without lying to yourself)) for context and common pitfalls.
Where to use this on MetricKit
Calculators
- Break-even CPM Calculator: Compute break-even and target CPM from CTR, CVR, AOV, and contribution margin assumptions.
- Break-even CTR Calculator: Compute the CTR required to break even (and hit a target) given CPM, CVR, AOV, and contribution margin.
- A/B Test Sample Size Calculator: Estimate sample size per variant for a conversion rate A/B test given baseline CVR, MDE, significance, and power.
- CPL to CAC Calculator: Convert cost per lead (CPL) into CAC using lead-to-customer rate (and compute targets).
- Break-even CVR Calculator: Compute the CVR required to break even (and hit a target) given CPM, CTR, AOV, and contribution margin.
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.