Double purchase

GTM Kit is actualluy checking if the purchase event has already been fired, to prevent tracking multiple purchases on refresh of the page.

Are you using any kind of cache?

Could you check the HTML of the page and see if the datalayer is added twice?

I think that the problem is that you are using multiple tracking tools. If this is a requirement you can use another datalayer name in GTM Kit. This can be set under: GTM Kit > General > Container > dataLayer variable name.

If this does not fix your problem you need to take a look at the HTML in the order received page and make sure that the purchase event is only added twice.

You don’t have to do anything else: https://developers.google.com/tag-platform/tag-manager/datalayer#rename_the_data_layer

You are welcome