Vantage importer allows single listing to be inserted in multiple categories
I don't know if this is a BUG or a feature of the "importer" tool.
The subscriber using the web interface does not have the ability to assign a listing to multiple categories.
If you create a CSV file and place comma separated list in the "listing_category" field, like:
The listing will be inserted and assigned to both categories "Apples" and "Cars".
The listing also correctly appears on the site under both categories.