Dim str() As String = _
      {"CCC 10", "AAA", "Block 4", "Block 1", "Block 10", "Block 10.1", 
       "Block", "Block 10.1 ab", "Block 10.1 aa", "Block 10.1", _
       "Block 10.2", "Block 2", "Block 3", "Block 10.10", "Block 4", _ 
       "CCC 1", "CCC 10", "CCC 2", "CCC 1"}
 
Array.Sort(str, New SpecialComparer)
 
str = (From el As String In str Distinct).ToArray