You can do this by either of two ways:
1. Sort the contents and in the blank column put the formula in row # 2 =if(A2=A1,"Duplicate,"") and fill down the formula till the last record... The word "Duplicate" will appear against the values which are duplicated.
2. You can create a Pivot table in another working sheet wherein put the Values in Columns and the count of Values in Data field... this will show you A.K. as column header in pivot and 2 as its count.