ToME: the Tales of Maj'Eyal

I'm currently running a cornac summoner in the infinite dungeon (the gametype, not the ID you can enter from after completing the game), i have reached the depth 20 and cleared the level.
I looked at my list of loots and noticed the Tooth of the Mooth in it

But the Tooth of the Mooth is an artifact i had already found a dozen of depth earlier and had equipped since then ?

Question is if you could equip two diggers could you dig twice as fast? One would think you'd need enough strength to effectively wield two diggers as well as have some form of dual weapon fighting that kinda says you're ambidextrous enough to use them.

A pick can't be used in the weapon slot so you can't equip two of them, could be interesting in some situation in which you are in a hurry to dig.

Anyways, on the same duplicate problem, my character is still alive in the ID and found the dagger artifact "Stars" on the 31st depth , that i had no use for my summoner and so transmogrified it.

But after clearing depth 32, i found the same dagger again.