Creating a report/Counting duplicate leads by a value

Creating a report/Counting duplicate leads by a value

Hello, 

I am in the process of a duplicate removal effort in Zoho. One thing I need before I charge ahead is a method to know HOW many duplicate lead profiles will need to be merged. Without downloading all of my data into excel, how can I count all of the profiles that meet the criteria: 

Count if lead.val_1 = NOT distinct 

Thank you