> ## Documentation Index
> Fetch the complete documentation index at: https://docs.sourcemedium.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Event + Journey Deduping

> How SourceMedium prevents double-counting when multiple event streams exist, and what “multi-source dedupe” means.

Some brands have multiple event sources (GA4, Snowplow, Heap, Elevar, Blotout, etc.). Those sources can record the *same* touchpoint within seconds of each other, creating the risk of double-counting.

For multi-source customers, SourceMedium uses **deduplication rules** to merge streams into a canonical view that preserves richness while preventing over-counting.

## High-level approach

For multi-source data, we consider touchpoints duplicates when core attributes match within a small time window. The dedupe fingerprint typically includes:

* Timestamp (rounded to seconds, in UTC)
* Standardized event name
* UTM source / medium / campaign (with NULL normalized)

Fields like `utm_content`, `utm_term`, and click IDs are preserved as enrichment but don’t always participate in the fingerprint (so you can still do creative-level analysis without inflating counts).

## Where this shows up

These patterns are most relevant when you query MTA / journey tables, like:

* `your_project.sm_experimental.obt_purchase_journeys_with_mta_models`

## Recommended analysis patterns

### Verify you’re not double-counting purchases

```sql theme={null}
SELECT
  COUNT(DISTINCT purchase_order_id) AS distinct_orders,
  COUNTIF(sm_event_name = 'purchase') AS purchase_event_rows
FROM `your_project.sm_experimental.obt_purchase_journeys_with_mta_models`
WHERE event_local_datetime >= DATETIME_SUB(CURRENT_DATETIME(), INTERVAL 30 DAY);
```

### Compare touchpoint volumes by source system

```sql theme={null}
SELECT
  COALESCE(NULLIF(LOWER(TRIM(source_system)), ''), '(unknown)') AS source_system,
  COUNT(*) AS touchpoints
FROM `your_project.sm_experimental.obt_purchase_journeys_with_mta_models`
WHERE event_local_datetime >= DATETIME_SUB(CURRENT_DATETIME(), INTERVAL 30 DAY)
GROUP BY 1
ORDER BY touchpoints DESC;
```

<Info>
  Single-source customers should remain unchanged; multi-source dedupe is only applied when multiple sources exist for the same order/journey.
</Info>