Additional Backlog column returned from API

When I use /rest/agile/1.0/board/${jiraBoardId}/configuration API to get kanban type configuration I always get additional Backlog column with no statuses. It looks like:

"columnConfig": {
		"columns": [{
			"name": "Backlog",
			"statuses": []
		}, {

There is no such column on the board. I know there is Kanban backlog idea idea but for the board I’m checking it, kanban backlog is not enabled.

Seems as not a problem, but I have a board with regular column called Backlog and from that board the API returns me 2 backlog columns.

Is this as designed behaviour or Backlog should not be returned when not enabled?