QGIS » QGIS Application

I want to export a subset of my features/attributes to geojson so that I can use them in a web map.

Given I've got a shapefile layer "cities" with attributes "important_stuff" and "irrelevant_stuff"
And I duplicate the layer to "cities_copy"
And I enable edit mode on "cities_copy"
And I open the attribute table for "cities_copy"
And I delete the "irrelevant_stuff" column from "cities_copy"
Then I see only the column "important_stuff" in the cities_copy attributes table (as expected)
And I save "cities_copy" as cities.geojson
Then I see cities.geojson was exported with only the "important_stuff" attribute (as expected!)
When I inspect the attributes table for "cities" I still see "important_stuff" and "irrelevant_stuff" (as expected)

But when I close QGIS and reopen my project
When I inspect the attributes table for "cities"
Then the attribute "irrelevent_stuff" is missing, and I only see "important_stuff" (!!!)

I suspect what's happening is that the layers are sharing a single shapefile storage mechanism, and edits to one of the layers in QGIS do no propagate to the Layer in QGIS (until that layer is reloaded from file).

I'm not exactly sure what I would expect to happen. My immediate thought is that editing should be disabled for duplicate layers until they have their own backend.

If this is expected behavior (that edits in a duplicate layer affect the storage for another layer) than we should consider updating other layers that are backed by this file.