duplicate_geography_id: GTFS validation rule Error
A locations.geojson feature id collides with a stop_id (or location_group_id): geography ids must be unique across stops.txt, locations.geojson and location_groups.txt.
What the rule checks
A locations.geojson feature id collides with a stop_id (or location_group_id): geography ids must be unique across stops.txt, locations.geojson and location_groups.txt.
Severity: error
An error marks data that breaks the GTFS specification. A journey planner or a rider app may refuse the file, or show a wrong version of it. Correct it before publishing the GTFS.
Where it applies
The rule applies to locations.geojson and stops.txt and location_groups.txt.
Finding and correcting it
Open the GTFS in GTFS Express. Reading is free, and the validation, by the MobilityData validator and the rules of GTFS Express itself, lists the occurrences of duplicate_geography_id with the file and rows involved. The correction is made in a draft, by hand or from a brief, with the licence: the corrected GTFS is validated again before it is delivered, and the change can be undone.
In the MobilityData validator
The MobilityData GTFS validator uses the same code, duplicate_geography_id. Its documentation describes each rule: MobilityData validator rules.