D7: How can I list duplicate entities based on the entity title and bundle, without custom coding
I'd look at the Entity Bulk Delete module. This module provides a Drush command that can bulk delete arbitrarily specified entity types. 

The caveat here is the module does not delete based on your specified logic of duplicate titles. For that, you can modify its EntityFieldQuery in the _entity_bulk_delete_query() function so it matches your criteria for deletion removal.