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
session.flush()
            subdag = dag.partial_subset(
                task_ids_or_regex={task_id},
                include_downstream=True,
                include_upstream=False,
            )
            end_date = execution_date if not future else None
            start_date = execution_date if not past else None
            subdag.clear(
                start_date=start_date,
                end_date=end_date,
                include_subdags=True,
                include_parentdag=True,
                only_failed=True,
                session=session,
                
                exclude_task_ids={task_id},
            )
            session.commit()
        flash(f"Marked {state} on {len(altered)} task instances")
        return redirect(origin)
    @expose('/confirm', methods=['GET'])
    @auth.has_access(
        [
            (permissions.ACTION_CAN_READ, permissions.RESOURCE_DAG),
            (permissions.ACTION_CAN_EDIT, permissions.RESOURCE_TASK_INSTANCE),
        ]
    )
    @action_logging
    def confirm(self):