XmlSerializer kan ikke klare at samme tag bruges til 2 forskellige typer.
Man kan naturligvis lave en wok around.
Imports System
Imports System.IO
Imports System.Linq
Imports System.Text.RegularExpressions
Imports System.Xml
Imports System.Xml.Linq
Imports System.Xml.Serialization
Namespace XmlFun
    Public Class Desg
        <XmlElement(ElementName := "TEXT")> _
        Public Property Text() As String
    End Class
    Public Class Record
        <XmlElement(ElementName := "DESG")> _
        Public Property Desg() As String
        <XmlElement(ElementName := "NAME")> _
        Public Property Name() As String
        <XmlElement(ElementName := "DESG2")> _
        Public Property Desg2() As Desg
    End Class
    Public Class Program
        Public Shared Sub Main(args As String())
            Dim xmlstr As String = "<Record>" & vbCr & vbLf & "    <DESG>TEST</DESG>" & vbCr & vbLf & "    <NAME>HANSEN</NAME>" & vbCr & vbLf & "    <DESG>" & vbCr & vbLf & "      <TEXT>HAMMEL</TEXT>" & vbCr & vbLf & "    </DESG>" & vbCr & vbLf & "  </Record>"
            Console.WriteLine(xmlstr)
            Dim doc As New XmlDocument()
            doc.LoadXml(xmlstr)
            Console.WriteLine(doc.DocumentElement.ChildNodes(0).FirstChild.Value)
            Console.WriteLine(doc.DocumentElement.ChildNodes(2).ChildNodes(0).FirstChild.Value)
            Dim xd As XDocument = XDocument.Parse(xmlstr)
            Console.WriteLine(xd.Root.Elements("DESG").ToArray()(0).Value)
            Console.WriteLine(xd.Root.Elements("DESG").ToArray()(1).Element("TEXT").Value)
            Dim ser As New XmlSerializer(GetType(Record))
            Dim r As Record = DirectCast(ser.Deserialize(New StringReader(Regex.Replace(xmlstr, "<DESG>(\s*<TEXT>.*</TEXT>\s*)</DESG>", "<DESG2>$1</DESG2>", RegexOptions.Singleline))), Record)
            Console.WriteLine(r.Desg)
            Console.WriteLine(r.Desg2.Text)
            Console.ReadKey()
        End Sub
    End Class
End Namespace
giver:
<Record>
    <DESG>TEST</DESG>
    <NAME>HANSEN</NAME>
    <DESG>
      <TEXT>HAMMEL</TEXT>
    </DESG>
  </Record>
TEST
HAMMEL
TEST
HAMMEL
TEST
HAMMEL