As reported by Gunnicus:
2 identical Pristine Fiery Loop of The Vile Apothecary (3-man Carn Dum) earrings do not give a set bonus in the game, but in LotroCompanion this bonus is added (+5658 Fate) to the character's characteristics. I had to add "-5658 Fate" to one of the earrings. Probably, this behavior is also with other identical 3-man Carn Dum earrings.
As reported by Gunnicus: 2 identical Pristine Fiery Loop of The Vile Apothecary (3-man Carn Dum) earrings do not give a set bonus in the game, but in LotroCompanion this bonus is added (+5658 Fate) to the character's characteristics. I had to add "-5658 Fate" to one of the earrings. Probably, this behavior is also with other identical 3-man Carn Dum earrings.