Hi
The issue isn't with listings.
It is the Search option that is causing the duplicates.
For instance, instead of bringing city name to make difference between search patterns of a particular category, the city name is omitted and all of the pages generated for that particular category for different cities have the same meta title, hence many duplicate pages. For instance instead of the meta title for category FOR SALE have city name attached to it for different cities, the city name can be omitted. So all the pages for generated for FOR SALE category for all available cities, have the same meta title. If there are 100 cities, then 100 pages having the same meta title.
There are so many scenarios like that