Problem
Certain items will show up in their unidentified form if you find another as loot, even if you've IDed them before. For example, if I identify a steel amulet as an AoLS, further ones I find will insist on showing up as "steel amulets".

"Some items (especially amulets) don't auto-identify when you get a new one if a type you've already identified." -- sorear's wiki

A non-comprehensive list:
* Orcish helmets
* Mithril, adamantium and eternium caps
* Diadems of beauty
* Helms of leadership
* Helms of mental stability
* Helms of water breathing
* Crowns of fire, ice, lightning and regeneration
* Mummy wrappings (the non-artifact ones)
* Spider shell armors (the +5 PV ones)
* Girdles of weight
* Girdles of greed
* Girdles of giant strength
* Amulets of balance
* Amulets of chaos
* Amulets of greed
* Amulets of health
* Amulets of hunger
* Amulets of life saving
* Amulets of light
* Amulets of order
* Amulets of protection from constructs
* Amulets of protection from undead
* Amulets of speed
* Necklaces of rabies resistance
* Necklaces of rapid healing
* Necklaces of the eye
* Pendants of mana
* Bracers of defense, protection, regeneration, resistance, speed and toughness (i.e. all of them)
* Orcish daggers (the 2d3+5 kind)

How to reproduce it
During normal gameplay, try to find any of the above items and identify it. Then, keep on playing until you find another one. It will show up on its unIDed form, even though you have one in your inventory and know what it is.

Notes
A hacked 1.2.0pr1 savegame where this situation has been artificially recreated via scrolls of amnesia and two stacks of items is available upon request.