Too Many Events — Which One Do I Pick?

You did the action once and three things fired. This is the single most common mess in the wild, and it is worth understanding why it happens before you choose, because the source tells you how trustworthy each candidate is.

Where the duplicates come from

• GTM's own auto-event: a Form Submit trigger makes GTM push gtm.formSubmit with gtm.element and friends attached.
• A plugin or theme: the forms plugin pushes its own form_submit (or wpcf7submit, gravityFormSubmission…) with its own field names.
• A developer's custom push: someone added formSubmitted by hand for a project two years ago.
• GA4 Enhanced Measurement: may already be collecting a generic form_submit with no business context at all.

So "the form submit" might be four different events, each firing at a slightly different moment with a different payload. Picking blindly is how you end up sending a conversion with a blank plan name, or counting every submit twice.

The three tests for a good event

Rank your candidates against these, in order:

And the third, which decides ties: can you target it uniquely? An event is only useful if you can write a trigger that fires on this case and nothing else — covered in the next lesson.

The richest-payload heuristic

When two candidates are equally reliable, prefer the one that already carries the data. Put the payloads side by side from the console and compare:

// Candidate A — plugin's custom event
{ event: "form_submit", formId: "demo-request", plan: "pro", value: 500 }

// Candidate B — GTM's native auto-event
{ event: "gtm.formSubmit", "gtm.elementId": "demo-request", "gtm.element": <form> }

A hands you plan and value directly — no extra work, nothing to scrape. B only knows the element. If both fire reliably once, A wins because it is richer. The trap is choosing B out of habit ("I always use the Form Submit trigger") and then spending an hour scraping the plan name back out of the DOM that A was handing you for free.