Prevent duplicate LinkedIn events

Generate a unique event ID

1. In your GoogUse a random string, UUID, or a combination of timestamp and transaction ID for uniqueness.le Ads account, go to Tools & Settings > Measurement > Conversions.
2. Generate the event_id in your website’s data layer or with a GTM Custom JavaScript variable.

Example Custom JavaScript Variable:

function() {
  return 'li_evt_' + Date.now() + '_' + Math.floor(Math.random() * 100000);
}

For e-commerce, combine order ID and timestamp for even stronger uniqueness:

function() {
 return 'li_order_' + {{Order ID}} + '_' + Date.now();
}

Push the event ID to the data layer

On the relevant event (e.g. purchase or lead), push the event_id into the data layer so both client and server have access:

Example (placed in your site’s JavaScript or GTM Tag)

window.dataLayer.push({
 event: 'purchase',
 event_id: 'li_evt_1721456789123_45678',
 value: 129.00,
 currency: 'EUR'
});

In case you you're using a tag to generate the event, use a custom HTML tag in GTM Web to push this structured event.

Add the Event ID to GTM web container (Insight Tag)

1. Create a Data Layer Variable for event_id.
2. Add the variable to your LinkedIn Insight Tag’s configuration:

Parameter name: event_id
Value: {{DLV – event_id}}

Reference the Event ID in GTM server container (CAPI Tag)

1. Create a Data Layer Variable for event_id in the server container.
2. Add the event_id to your LinkedIn CAPI HTTP Request payload:

json
{
 "event_name": "Purchase",
 "event_time": {{Timestamp}},
 "event_id": "{{event_id}}",
 // ...user_data and custom_data
}

Test deduplication

1. Use GTM Preview mode to ensure the same event_id is present in both client- and server-side events.
2. In LinkedIn Campaign Manager, use diagnostics or conversion logs to verify deduplication is working.
3. Check that only one conversion is counted per user action.

Best practices

Useful resources