they are called Good Overs.
That's right. "Good Over" notes are much rare than most change-overs. Apparently they are notes with an old signature combination (already printed on sheets) and used later in a newer (more recent) signature combination typically high serial number range.
On Page 283 of the 2013 Charlton (25th Ed) it explains that:
""... nearly all of the $10 notes were signed Crow-Bouey. However the Lawson-Bouey signatures made a surprising reappearance on notes EET 9360000 to EET 9999999, when 640,000 Lawson-Bouey notes were salvaged from defective sheets and assigned these numbers. Recently $10 notes signed Lawson-Bouey have been reported in series EEP (over 9,000,000) and EES as well. They appear to be quite rare."
This phenomenon (I believe) also happened with very few BIRDS EPW $5.00 with the old Bonin-Thiessen signature combination applied to HNB (& it could be possible that the few AUG - AUN were another type of good-over -perhaps testing the new Thiessen-Crow signature combination on older Crow-Bouey AUG-AUN prefixed serial numbers).