We can't solve this problem with using report. So, I'll show you the solution which using node ( with jsforce and lodash ).
The summary of the process is as follows.
- login your organization
- retrieve full leads with full fields ( See also: How to get Salesforce sObject's fields information by node - It's All Writing. )
- group the leads by lead's name
- count each group's element. If the count greater than 1, the group is the same name group.
- print the same name group informations ( Id, Name, Email and Company on CSV format ).