I've had two people verify it works this way currently but:

If you mark an item as owner furnished first, you cannot select do not order.

If you mark an item as do not order first, you can select owner furnished and both are considered true.

This seems like a bug, but in general if something is marked as OFE, it would also be DNO - but since it's unable to be selected in that order, there have been some situations where they are not appropriately caught in filters.