How about 
Sub GetUnique()
   Dim cl As Range
   
   With CreateObject("scripting.dictionary")
      For Each cl In Range("J4", Range("J" & Rows.Count).End(xlUp))
         .Item(cl.Value) = Empty
      Next cl
      For Each cl In Range("S4", Range("S" & Rows.Count).End(xlUp))
         .Item(cl.Value) = Empty
      Next cl
      Range("A1").Value = Join(.keys, ", ")
   End With
End Sub
This replaces all your code