I think maybe this key has reused another item’s ID.
I have a character that has not yet gone to Forgotten Reach. He has, in his bags, what used to be an Irontide Lockbox key from Mechagon. Now when I mouse over it, it shows up as Key of Bound Earth. I know it’s still the same item I had, because I have what I think is the built in tooltip: “An unusual Primordial Key,” but also tooltips added by an addon, “Key drops from Seaspit and Seaspray mobs,” and other addon text relating to both Mechagon and Forbidden Reach.
It’s not the addon, because things are similarly confusing if you go look at Wowhead. For example, the page for this key says it unlocks both Irontide Lockbox and Primordial Earth Cache.
I don’t know how this is going to work when I go to Forbidden Reach. I don’t want to use up this key; I was keeping it for a reason and therefore haven’t tried to open the Mechagon lockbox. But I don’t know if I will be able to loot another in Forbidden Reach - in Mechagon you can loot this key at most once per day.