What relic weapons get from FATEs?

[Nova_Dresden]

Are you able to confirm this?

I farmed up all 12 atma stones and placed them on a retainer.

This was over 3 months ago.

I usually Fate/Hunt Pt as Healer wearing Zenith Rod.

In these 3 months I've never seen a duplicate atma drop.

Is it possible that after reaching all 12, you cannot collect more until you upgrade an item? Anecdotal but true. 3~ months no atma

Yes, they stack. Yes you can get multiples of the same one. My friend got 4 atma in one zone while trying to farm my one. Animus and above cause Alexandrite to drop instead of atma, so only zenith will get you atma.