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
return redirect(request.referrer or url_for('Airflow.index'))
        execution_date = timezone.parse(execution_date)
        from airflow.api.common.experimental.mark_tasks import set_state
        to_be_altered = set_state(
            tasks=[task],
            execution_date=execution_date,
            upstream=upstream,
            downstream=downstream,
            future=future,
            past=past,
            state=state,
            commit=False,
        )
        details = "\n".join(str(t) for t in to_be_altered)
        response = self.render_template(
            "airflow/confirm.html",
            endpoint=url_for(f'Airflow.{state}'),
            message=f"Here's the list of task instances you are about to mark as {state}:",
            details=details,
        )
        return response
    @expose('/failed', methods=['POST'])
    @auth.has_access(
        [
            (permissions.ACTION_CAN_READ, permissions.RESOURCE_DAG),
            (permissions.ACTION_CAN_EDIT, permissions.RESOURCE_TASK_INSTANCE),
        ]
    )
    @action_logging
    def failed(self):