Connected content making 2 calls

Hi
I have this connected-content in email template; but when I send out, its always making two POST API calls; I'm adding customers in a list in a survey module and every time my canvas sends out email; it adds customers twice.
Is there any way to prevent this?

Thanks
//Waqas

{% capture payload %}
{
    "contactDetails": "{{${email_address}}}"
}
{% endcapture %}
{% connected_content 
   {{ url }}
   :method POST
   :headers {
     "Content-Type": "application/json",
     "X-API-KEY": "xxx"
   }
   :body {{payload}}
   :content_type application/json
   :no_cache
   :save add_response
%}