Misconfigured triggers : Overly broad settings can lead to duplicate events. For example, a trigger configured for all pages may fire multiple times if it is also associated with a specific click.
GTM Code Duplication – Inserting GTM code more than once on your website causes the tags to fire multiple times.
Multiple tags with the same trigger : If two tags are associated with the same trigger, they will both fire simultaneously, creating duplications.
Double Triggering in SPA Applications : In Single Page Applications (SPA) , events can fire multiple times if triggers based on history changes or custom events are not handled properly.
Tag sequencing errors : Tags that are not sequenced correctly fast food email list can fire multiple times by a single user action.
GTM container added multiple times : Sometimes the GTM container may have been inserted more than once in the site code.
GA4 Integration Mistakes : Poorly managed configurations between GTM and GA4 can result in duplicate events if event and filter settings are not properly customized. For example, a common mistake is to configure GTM and the GA4 Global Tag at the same time, which results in a duplicate event. Another example would be creating events in GTM and GA4 at the same time. It is recommended to create the events in one place if both are linked.
How to identify duplicate events
1. Google Analytics
In Google Analytics, you can look for signs of duplicate events by reviewing the “Events” report and checking if the event count is abnormally high relative to user interaction. If the numbers seem inflated, it could be an indication of duplication.
2. Preview in Google Tag Manager
Google Tag Manager offers a “Preview” tool that allows you to see when and how tags are triggered in real time. Use this tool to simulate user interactions on your website and see if the same event is triggered more than once by a single click or action.
3. Debugging with browser extensions
There are browser extensions like “Tag Assistant” or “Data Layer Inspector” that allow you to check which tags are being fired and if there are duplicates in the data sent to Google Analytics or other tools.
How to fix duplicate events
Review triggers and tags : Make sure you don't have multiple tags firing from the same trigger. If so, combine the events into a single tag or use different triggers to avoid duplication. Check that triggers aren't firing in situations where they shouldn't. For example, on a click trigger, make sure it's set to fire only on the button you're interested in, and not on any clicks within the page.