When it creates a reply, the Watch Events webhook is triggered again.
You need to find some data in the Watch Events output bundle that allows you to create a filter to filter out (ignore) own/self-replies.
Please provide the output bundles of the modules by running the scenario, then click the white speech bubble on the top-right of each module, save the bundle contents in your text editor as a bundle.json file, and upload it here into this discussion thread.
Providing the output bundles will allow others to replicate what is going on in the scenario even if they do not use the external service.
This will allow others to better assist you. Thanks!