关于Hibernate 重复获取主键和关联类的外键的疑问

假定Customer类和Order类之间为双向一对多关联关系.
Customer类包含的属性:

[java]
/**对象OID*/
private Long id;
/**Customer对象的姓名*/
private String name;
/**Customer对象的年龄*/
private int age;
/**与Customer对象的订单*/
private Set<Order> orders=new HashSet<Order>();

hibernate映射文件:
[html]
<class name="Customer" table="customers">
    <id name="id" type="long" column="id">
        <generator class="native" />
    </id>

    <property name="name" type="string" column="name" />

    <property name="age" type="int" column="age" />

    <set name="orders" cascade="all" inverse="true" lazy="true">
        <key column="customer_id" />
        <one-to-many class="Order" />
    </set>

</class>

Order类包含的属性:
[java]
/**对象OID*/
private Long id;
/**Order 对象的订单号*/
private String orderNumber;
/**Order 对象的订单价格*/
private double price;
/**与Order 对象关联的Customer对象*/
private Customer customer;

hibernate映射文件:
[html]
<class name="Order" table="orders">

   <id name="id" type="long" column="id">
     <generator class="native"/>
   </id>

   <property name="orderNumber" type="string" column="orderNumber" length="15" />

   <property name="price" type="double" column="price" />

   <many-to-one name="customer" column="customer_id" class="Customer" />

</class>

假设数据库中存在的数据为:
cusomters表

orders表:

以下为测试代码:

[java]
List result=session.createQuery("select c from Customer as c inner join c.orders where c.name like 'T%'")
.list();
Iterator it = result.iterator();
Customer customer=(Customer) it.next();
System.out.println(customer.getOrders().size());

Hibernate生成对应的SQL语句为:
[sql]
Hibernate:
    select
        customer0_.id as id4_,
        customer0_.name as name4_,
        customer0_.age as age4_
    from
        customers customer0_
    inner join
        orders orders1_
            on customer0_.id=orders1_.customer_id
    where
        customer0_.name like 'T%'
Hibernate:
    select
        orders0_.customer_id as customer4_4_1_,//重复字段
        orders0_.id as id1_,//重复字段
        orders0_.id as id5_0_,
        orders0_.orderNumber as orderNum2_5_0_,
        orders0_.price as price5_0_,
        orders0_.customer_id as customer4_5_0_
    from
        orders orders0_
    where
        orders0_.customer_id=?

疑问:
    上述sql语句中,注释重复字段与下面的字段重复了,为什么要重复检索orders的主键id和外键customer_id字段
    另:
    上述采用内链接方式检索,但其实做外连接,迫切做外连接,单表查询也会重复检索主键和外键字段

补充：软件开发 , Java ,