Extract unique values

Hi, I really hope you dont mind taking a minute to give me some help. I would really appreciate it. I have an excel file e.g.
Col A Col B
Item1 101
item2 102
item3 102
item4 103
item4 104
item5 105
item6 105
I need to extract and remove the unique value rows from the file and just be left with the rows which have the number in column b occuring more than one. I hope I have explained that okay?
I want 101,103 and 104 cut out of the file and into another spreadsheet any ideas how I might do this. I am using excel 2010

thanks you in advance for your help and time