I have a Joomla website with existing analytics done by a GTM tag and I need to add another image tag (1x1 pixel) from a separate GTM container. I set the event name for the additional GTM container to a different name from from the existing GTM container (default 'gtm.js') so that the new tag only fires under the specified event. The new container tested out fine in a blank HTML page, but when it is put in the website, it ends up firing twice. I know that because Firebug showed 2 1x1 pixels being loaded and I mark each request with a randomly-generated UID to distinguish them on the server side.

I suspect this being caused by having multiple GTM container tags but want to check whether anyone has run into this problem before? As of now, I could not verify nor fix the double counting problem.

3 Answers 3


Well actually you can do this by changing the data layer name - see this:

It is possible to implement multiple containers on the same page. By default, each container will use a common data layer. If you'd like each container to use its own data layer, you may modify the data layer name in one or more of your container snippets.


I can verify that having multiple containers on the same site causes tags to fire twice. I have found no documentation to support the use of two containers from the Google Tag Manager dev docs. As of now, this appears to be a limitation of GTM.

  • Thanks. This only means that when a client is already using GTM and refuses to hand over access, we just have tell them to half the numbers :D.
    – fred
    Jul 23, 2013 at 8:06

You can also implement GTM with the same data layer name. I recommend using Google tag assistant for Chrome.

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