Private Function GetNewFilename _
       (ByVal Filename As String) As String
 
        Dim d As String = IO.Path.GetDirectoryName(Filename)
        Dim f As String = IO.Path.GetFileNameWithoutExtension(Filename)
        Dim ext As String = IO.Path.GetExtension(Filename)
 
        If Not IO.File.Exists(Filename) Then Return Filename
 
        Dim i As Integer = 1
        Dim fi As String = f
        Do
            i += 1
            fi = f & i.ToString
        Loop While IO.File.Exists(IO.Path.Combine(d, fi & ext))
 
        Return IO.Path.Combine(d, fi & ext)
    End Function

 
  Dim filename As String = "C:\daten\ttt.csv"
  For i As Integer = 1 To 10
      IO.File.Create(GetNewFilename(filename))
  Next i