序列化期间Xml文件中的多个根去极化

我正在做Xml序列化，但遇到了一个错误，我有将近一个星期的时间，我有一个简单的网页，比如

FirstName文本框： LastNameTextBox： EmailTextBox：

提交按钮

我有两个类叫做Customer和Customer List customer类如下所示

namespace XmlSearlizeProject.Classes
{
    [Serializable]
    [XmlRoot("CustomerData")]
    public class Customer
    {
        string id = default(string);
        string firstName = default(string);
        string lastName = default(string);
        string email = default(string);
        public Customer()
        {

        }
        public Customer(string id, string firstName, string lastName, string email)
        {
            CustomerId = id;
            FirstName = firstName;
            LastName = lastName;
            Email = email;

        }
        [XmlElement("CustomerId")]
        public string CustomerId
        {
            get
            {
                return this.id;
            }
            set
            {
                this.id = value;
            }
        }
        [XmlElement("FirstName")]
        public string FirstName
        {
            get
            {
                return this.firstName;
            }
            set
            {
                this.firstName = value;
            }
        }
         [XmlElement("LastName")]
        public string LastName
        {
            get
            {
                return this.lastName;
            }
            set
            {
                this.lastName = value;
            }
        }
         [XmlElement("CustomerEmail")]
        public string Email
        {
            get
            {
                return this.email;
            }
            set
            {
                this.email = value;
            }
        }
    }
}

<?xml version="1.0" encoding="utf-8"?>
<ArrayOfCustomer xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <Customer>
    <CustomerId>34f15068-4331-4253-8660-d1ce2199ed6d</CustomerId>
    <FirstName>haseeb</FirstName>
    <LastName>khan</LastName>
    <CustomerEmail>abc@hotmtail.com</CustomerEmail>
  </Customer>
</ArrayOfCustomer>

CustomerList类是这样的

namespace XmlSearlizeProject.Classes
{
    [Serializable]
    public class CustomerList:List<Customer>
    {
    }
}

现在我的问题是，当我使用序列化函数添加第一个客户时，XML文件如下所示

namespace XmlSearlizeProject.Classes
{
    [Serializable]
    [XmlRoot("CustomerData")]
    public class Customer
    {
        string id = default(string);
        string firstName = default(string);
        string lastName = default(string);
        string email = default(string);
        public Customer()
        {

        }
        public Customer(string id, string firstName, string lastName, string email)
        {
            CustomerId = id;
            FirstName = firstName;
            LastName = lastName;
            Email = email;

        }
        [XmlElement("CustomerId")]
        public string CustomerId
        {
            get
            {
                return this.id;
            }
            set
            {
                this.id = value;
            }
        }
        [XmlElement("FirstName")]
        public string FirstName
        {
            get
            {
                return this.firstName;
            }
            set
            {
                this.firstName = value;
            }
        }
         [XmlElement("LastName")]
        public string LastName
        {
            get
            {
                return this.lastName;
            }
            set
            {
                this.lastName = value;
            }
        }
         [XmlElement("CustomerEmail")]
        public string Email
        {
            get
            {
                return this.email;
            }
            set
            {
                this.email = value;
            }
        }
    }
}

<?xml version="1.0" encoding="utf-8"?>
<ArrayOfCustomer xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <Customer>
    <CustomerId>34f15068-4331-4253-8660-d1ce2199ed6d</CustomerId>
    <FirstName>haseeb</FirstName>
    <LastName>khan</LastName>
    <CustomerEmail>abc@hotmtail.com</CustomerEmail>
  </Customer>
</ArrayOfCustomer>

34f15068-4331-4253-8660-d1ce2199ed6d
哈西布
可汗
abc@hotmtail.com

但是，当我尝试添加另一个客户时，使用相同的序列化函数和相同的网页，那么我的XML文件如下所示

<?xml version="1.0" encoding="utf-8"?>
<ArrayOfCustomer xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <Customer>
    <CustomerId>34f15068-4331-4253-8660-d1ce2199ed6d</CustomerId>
    <FirstName>haseeb</FirstName>
    <LastName>khan</LastName>
    <CustomerEmail>abc@hotmtail.com</CustomerEmail>
  </Customer>
</ArrayOfCustomer><?xml version="1.0" encoding="utf-8"?>
<ArrayOfCustomer xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <Customer>
    <CustomerId>924e5fe3-d5ce-41c2-a850-4d3da1e44f91</CustomerId>
    <FirstName>ammar</FirstName>
    <LastName>khan</LastName>
    <CustomerEmail>xyz@hotmail.com</CustomerEmail>
  </Customer>
</ArrayOfCustomer>

34f15068-4331-4253-8660-d1ce2199ed6d
哈西布
可汗
abc@hotmtail.com
924e5fe3-d5ce-41c2-a850-4d3da1e44f91
安马尔
可汗
xyz@hotmail.com

我不明白如何修复这个错误，当我添加新客户时，我需要这样的Xml文件

<?xml version="1.0" encoding="utf-8"?>
<ArrayOfCustomer xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <Customer>
    <CustomerId>34f15068-4331-4253-8660-d1ce2199ed6d</CustomerId>
    <FirstName>haseeb</FirstName>
    <LastName>khan</LastName>
    <CustomerEmail>abc@hotmtail.com</CustomerEmail>
  </Customer>
  <Customer>
    <CustomerId>924e5fe3-d5ce-41c2-a850-4d3da1e44f91</CustomerId>
    <FirstName>ammar</FirstName>
    <LastName>khan</LastName>
    <CustomerEmail>xyz@hotmail.com</CustomerEmail>
  </Customer>
</ArrayOfCustomer>

34f15068-4331-4253-8660-d1ce2199ed6d
哈西布
可汗
abc@hotmtail.com
924e5fe3-d5ce-41c2-a850-4d3da1e44f91
安马尔
可汗
xyz@hotmail.com

---

请帮助我解决这个问题已经一个星期了，我已经尝试了所有的方法，但是能够解决这个错误。如果有人帮助我，我将感谢他