If you look in the contruction set a number of items has some double items that differ in their id by some designator.

For example there is ebony_bracer_right and ebony_bracer_right_tgeb. Same way there is a bonemold_gah_julan_helm and also bonemold_gah_julan_nhda.

Also there is a "left gauntlet of the horny fist" and also "gauntlet _horny_fist_l".

What are these designators tgeb and nhda and why are these double items? I am a fanatic collector so I just want to know whether I can actually tell the different in the game and own both.

The _nhda on the bonemold helm is a seperate helm in a Hlaalu quest where you impersonate a dead Redoran in order to intercept secret orders from Neminda.

The _tgeb is on a pair of ebony bracers that do not exist within the game. They have the _tg suffix, so they must have been originally intended for a Thieves Guild quest that was later scrapped.

There are many, many items that are 'renamed' in their IDs. This is so they can be triggered indivudually in dialogue or script. In some cases, there is need to find a rare variety of an otherwise common item, such as the Roland's Tear variety of the Golden Kanet. They rename the ID of the flower to give it a property that can be triggered when the PC speaks to the questgiver who asked for the flowers.

There are two types of addamantium armor too. One one them is misspelled.

Lucky you didn't say which one -- this could've gotten embarrassing if you did.