You can first group by the fields from which you want the records to be unique. then add a field count(*) to retrieve the no. of rows in the group.
so this way you would be able to find out the no. of rows duplicate.
Such as :-
Select City,Weather,Count(*) as [No. of Common Rows] from tblCity Group by City,Weather
Darpan Gogia
darpan.kumar@india.birlasoft.com