So in Primm in the second NCR tent (not the one with the captain) there is an armor box that spawns a generic NCR armor except that it has (2) marked after it as if there would be 2 items in one.
If you drop this particular armor it falls down as one single item and no more trouble comes of it, but if you try to Fix the armor with itself the game crashes and if you equip it your inventory will be left with one extra version of the armor but if you drop it the game crashes

Just to make it a bit clearer

NCR armor spawns with (2) after its name in NCR tent
-> drop it = falls down as one single armor and can be picked up and equipped and no more harm comes from it
-> Try to fix the armor with the duplicate that spawned with it = Game crashes
-> Equip the other part of the armor and drop the second part = Game crashes