Event duplication can occur when the same tracking tag is installed multiple times on your store. This usually leads to inflated metrics such as page views, add to cart, or purchase events appearing more than once.

This guide will help you review your setup and identify possible causes of duplicated events.

1. Reasons why event duplication happens

One common cause of duplicate events is when the same Google Tag Manager (GTM) ID is added in more than one place.

For example:

• Added directly in the theme code
• Added through a Shopify preference setting
• Added through a third-party app

When the same GTM container loads twice, it can trigger duplicate tracking events.

2. Check events using Google Tag Assistant

You can use Google Tag Assistant to detect duplicate tags or events.

How to check

1. Go to https://tagassistant.google.com/
2. Enter your store domain and click Connect
3. Wait for Tag Assistant to connect to your site
4. Perform some test actions on the store (for example: view a product or add to cart)
5. Return to Tag Assistant and review the events

If one tag fired multiple times for a single action, it usually means the tracking tag has been installed more than once as shown in the screen below:

3. Conclusion

Event duplication usually occurs when the same tracking event is triggered from multiple sources. This can lead to inaccurate analytics data and inflated metrics. If you are unsure where the GTM ID was added, you may need to review the theme code. If necessary, ask your developer team to help check the theme and identify where the GTM script is installed.

Updated on: 12/03/2026