Facebook Pixel shopify integration: AddToCart Event firing Twice

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Topic summary

A Shopify store owner is experiencing duplicate Facebook Pixel AddToCart events, with the pixel firing twice each time a customer adds a product to their cart. The Facebook Pixel Helper confirms the pixel is activated twice on the same page, causing tracking errors.

Root Cause Identified:
The issue was traced to an Ajaxify widget that had been modified in the theme files. Ajax cart functionality is a common culprit for duplicate pixel firing.

Common Solutions Suggested:

  • Remove any manual pixel code from theme files (theme.liquid) if the pixel is already installed via Shopify admin preferences
  • Check Facebook Events Manager for duplicate manual events created through the Event Setup Tool and delete them
  • Use browser dev tools to identify which scripts are initiating the duplicate events
  • Verify GTM isn’t triggering additional pixel events in Preview Mode
  • Consider using dedicated Shopify apps that automatically deduplicate events

Key Recommendation:
Only use the Facebook Pixel through Shopify’s admin area (Online Store > Preferences), not through both admin and manual theme code. Multiple participants confirmed fixing their issues by removing Ajax-related conflicts or duplicate pixel installations.

Summarized with AI on October 31. AI used: claude-sonnet-4-5-20250929.
6

Hey MaximGj, I have been through your issues and screencast.
One possibility for the cause of this error is the manual event which might have been setup through the event setup tool and though you have already connected the pixel through shopify partner integration. It becomes a possibility that both of the events are firing at once, first one from manual setup and other one from partner integration.

solution for this is as per the following steps.
go to business settings > events manager > on the right hand side you’ll find the event type (all/custom events) [screenshot attached].

click on the custom event and you’ll find all the events setup through the manual setup tool, find add to cart & click on it, then click on manage events and delete it.
you issue is sorted, test your events for a confirmation.

I hope this resolves your issue. Please feel free to revert back to us if it does.

Regards

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