Do identical bonuses from random properties of different Artifacts stack?

Question

Some Artifacts have Major/Minor Beneficial/Detrimental Properties, rolled from the appropriate table.

If I were to have two different attuned Artifacts, both with, say, the Minor Beneficial Property of "While attuned to the artifact, you gain a +1 bonus to Armor Class.", would I have a +2 or +1 AC bonus?

From the DMG Errata on Combining Game Effects (p. 252):

Different game features can affect a target at the same time. But when two or more game features have the same name, only the effects of one of them—the most potent one—apply while the durations of the effects overlap. [...] Game features include spells, class features, feats, racial traits, monster abilities, and magic items.

"Artifact property" isn't listed, which is evidence for +2. But Artifacts are magic items, which may mean it should only be +1 instead. Which is correct?

Answer 1

They stack, unless you've got two of the same artefact

I think you've misunderstood the rule about combining effects slightly; the text isn't meant to suggest that magic items, in general, do not stack with each other. The intended reading is that magic items with the same name don't stack, but otherwise they can combine together.

That means that, for instance, if you already have one ring of protection, you don't get any benefit by attuning to a second ring of protection; since the two magic items have the same name, their effects do not combine. However, you could instead attune to a cloak of protection, and despite the fact that these two items both provide exactly the same actual benefit, because they have different names, their effects can combine.

Thus, if you have two different artefacts - say, the Axe of the Dwarven Lords and the Sword of Kas - and both of them have the +1 AC minor property, because they are game features with different names, the effect stacks to an overall +2 bonus.

However, if you had two Orbs of Dragonkind which both had the +1 AC property, because those artefacts have the same name, the effect would not combine - you only get +1 AC.

Answer 2

Yes, they stack.

You have cited the relevant rule. Since two different artifacts have different names, their properties will stack, even if they have the same properties.

This works for other items too. A Cloak of Protection and a Ring of Protection will both apply when worn, even though they do the same thing.