Question : excel checking unique values

Hi,
If I have two column in excel Column A and Column B, How do I group my selection base on Column A and mark unique value in column B ?

Column A  Column B
server A      9.0.4022.00
server A      9.0.4022.00
server A      9.0.4022.02
server A      9.0.4022.03
server A      9.0.4022.04

Answer : excel checking unique values

Please see attached file to see possible solutions (formula and conditional formatting).

solution.xls (21 KB)  (File Type Details) 

solution