In the UI it would be nice to duplicate the selected connection, in the menu "With Selected". 

The copy would be set with the same name plus some suffix (_copy, _1, whatever) and it is useful for when you have a connection with all equal fields except something in a particular one. 
airflow/www/views.py
"""Triggers DAG Run."""
        dag_id = request.values.get('dag_id')
        origin = get_safe_url(request.values.get('origin'))
        request_conf = request.values.get('conf')
        if request.method == 'GET':
            
            default_conf = ''
            dag = current_app.dag_bag.get_dag(dag_id)
            doc_md = wwwutils.wrapped_markdown(getattr(dag, 'doc_md', None))
            if request_conf:
                default_conf = request_conf
            else:
                try:
                    default_conf = json.dumps(dag.params, indent=4)
                except TypeError:
                    flash("Could not pre-populate conf field due to non-JSON-serializable data-types")
            return self.render_template(
                'airflow/trigger.html', dag_id=dag_id, origin=origin, conf=default_conf, doc_md=doc_md
            )