Collected Firestone Shards reappear in Draconic Mons

I noticed today that Firestone Shards I had already collected earlier reappeared on the map (to make sure it I hadn't missed them before I checked the count in the Rock Collector achievement and it stayed the same after picking it up).Since the ones I saw were in quite obvious locations, I might have picked them up a year or so ago when I first entered the map. I recently started doing the achievement though and try getting as far as I can, without using a guide; I would appreciate if the task wouldn't be made more complicated than it already is :)
I seem to remember reading on reddit that Golden Badges reappeared for players in the Silverwastes, so there might be some bigger underlying problem.