Public Class Form1
 
   Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As _
     System.EventArgs) Handles Button1.Click
 
      Dim l As New List(Of String)
 
      l.Add(Me.TextBox1.Text.Trim)
      l.Add(Me.TextBox2.Text.Trim)
      l.Add(Me.TextBox3.Text.Trim)
      l.Add(Me.TextBox4.Text.Trim)
      l.Add(Me.TextBox5.Text.Trim)
      l.Add(Me.TextBox6.Text.Trim)
      l.Add(Me.TextBox7.Text.Trim)
 
      If Me.CheckForDuplicate(l) Then
         MessageBox.Show("Doppelte vorhanden")
      Else
         MessageBox.Show("Keine doppelten Einträge")
      End If
 
   End Sub
 
   Private Function CheckForDuplicate(ByVal InList As List(Of String)) As _
     Boolean
      Return (InList.Distinct.Count <> InList.Count)
   End Function
 
End Class

Gru?
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Snoopy sagt - vb@rchiv find ich gut...
Schon gesehen? OSMMapViewer V2 Control