XmlSerializer插入2个xml声明

我正在编写一些代码来序列化一些体素模型数据。序列化器代码工作得很好，除了它插入了3个xml声明，这会在试图反序列化时导致错误。

我代码:

static Encoding encoding = new UTF8Encoding(false);
public void Save(string path) {
    /* trick to remove unessessarynamespace attributes */
    var ns = new XmlSerializerNamespaces();
    ns.Add("", "");
    var serializer = new XmlSerializer(typeof(VoxelData));
    var stream = new StreamWriter(path, false, encoding);
    serializer.Serialize(stream, this, ns); // this refers to the VoxelData class
    /* converts a dictionary to an array of a temporary serializable type */
    if (voxels != null) {
        System.Type[] otherTypes = { typeof(Vector3Serializer) };
        var attrSerializer = new XmlSerializer(typeof(voxelsave[]), null, otherTypes, new XmlRootAttribute() { ElementName="voxels" }, ""); // new XmlRootAttribute() { ElementName = "attributes" }, );
        voxelsave[] voxelSave = voxels.Select(kv => new voxelsave() { data = kv.Value, position = new Vector3Serializer(kv.Key) }).ToArray();
        attrSerializer.Serialize(stream, voxelSave, ns);
    }
    /* converts a dictionary to an array of a temporary serializable type */
    if (attributes != null) { 
        System.Type[] otherTypes = { typeof(Vector3Serializer) };
        var attrSerializer = new XmlSerializer(typeof(attributesave[]), null, otherTypes, new XmlRootAttribute() { ElementName = "attributes" }, ""); // new XmlRootAttribute() { ElementName = "attributes" }, );
        attributesave[] attributeSave = attributes.Select(kv => new attributesave() { key = kv.Key, value = kv.Value }).ToArray();
        attrSerializer.Serialize(stream, attributeSave, ns);
    }
    stream.Close();
}

以及一些序列化类的片段:

[XmlType(TypeName = "attribute")]
public class attributesave {
    [XmlAttribute]
    public object key;
    public object value;
}
[XmlType(TypeName = "voxel")]
public class voxelsave {
    public Vector3Serializer position;
    public Voxel data;
}
[System.Serializable]
public class VoxelData {
    [XmlIgnore]
    private Dictionary<Vector3, Voxel> voxels = new Dictionary<Vector3, Voxel>();
    [XmlIgnore]
    public Dictionary<object, object> attributes = new Dictionary<object, object>();
    [XmlAttribute("scale")]
    public float scale = 1.0f;
 ...
}

下面是一个输出示例:

<?xml version="1.0" encoding="utf-8"?>
<VoxelData scale="1" />
<?xml version="1.0" encoding="utf-8"?>
<voxels>
  <voxel>
    <position x="0" y="0" z="0" />
    <data color="RGBA(1.000, 0.000, 0.000, 1.000)" scale="1" />
  </voxel>
</voxels><?xml version="1.0" encoding="utf-8"?>
<attributes>
  <attribute key="handle">
    <value d3p1:type="vector3" x="0" y="0" z="0" xmlns:d3p1="http://www.w3.org/2001/XMLSchema-instance" />
  </attribute>
</attributes>

你可以看到有3个xml?标签，其中2个不应该在那里。它们在试图反序列化时抛出错误，如果我删除第二个标签，它们反序列化很好。

我的问题是:为什么要插入第二个标签，我如何阻止它?

var attrSerializer = new XmlSerializer(
          typeof(voxelsave[])
          , new XmlWriterSettings {OmitXmlDeclaration = true}
          , ....)