How to find and fix duplicate conversion tags in Google Tag Manager

Why duplicates happen

• Two tags send the same event, often after a migration where the old tag was never removed.
• Two triggers overlap, for example a custom event trigger and an All Pages trigger on the same tag.
• A tag was copied for a test and left running.
• The thank-you page can be refreshed, and no unique ID is sent for deduplication.

How to spot them

Open Preview mode and complete a test purchase. Under the purchase event, look at Tags Fired. The same tag appearing twice, or two tags that send the same event to the same property, is a duplicate.

Also scan the workspace tag list for names ending in "copy" or "old", and check GA4 DebugView for repeated events.

How to fix them

• Keep one tag per conversion and remove the rest once Preview confirms nothing depends on them.
• Give each tag one clear trigger and remove overlapping triggers.
• Send a unique event_id or transaction_id with every conversion so platforms can deduplicate.
• Publish with a version note so the change is easy to roll back.

When two tags are not duplicates

A GA4 purchase event and a Google Ads purchase conversion firing on the same order is normal, because they report to different platforms. A duplicate means the same platform receives the same conversion twice, from two tags or from two triggers on one tag.

Check the tag type and the measurement or conversion ID before you delete anything. Two tags with the same ID and the same event are the ones to look at.

Confirm the fix worked

• Repeat the test purchase in Preview mode. Each conversion tag should now appear once under the purchase event.
• Refresh the confirmation page and check that no second conversion is recorded.
• Watch the platform reports for a few days. Conversions should drop to match your real order count.

Let Dr.GTM find them for you

Dr.GTM flags the same tracking event sent by more than one tag, duplicate trigger configurations and conversion tags with no deduplication ID, and lists the affected items so you can fix them in minutes. It reads your container with read-only access.