The Portal "Edit" menu has a "Report Invalid Portal" button which has the "Duplicate of another Portal" option. In the past we have used this option to report very obvious duplicate portals which should be identified by their photos but those reports were mostly rejected by the NIA operatives. Later we began to use the "Edit Location" button to report duplicates which had both similar photos and were in a short proximity. This kind of duplicate reportings were more succesful than using the "Duplicate" option.
Lately we are observing that the Nia operatives aren't merging the Portals reported with "Location" corrections. We've started to have duplicate Portals which are side by side with just 1-5 meters of distance. Is this some kind of a new Portal policy by Niantic and how can we merge those siamese Portals? Did you observe something like this, too?