Game Mechanics: Grachinst & PBAE Killed Repops

[Handull]

I have killed about 12 full cycles of the goblin fort in WW and the camp just across the bridge, all using the lvl 52 druid pbae spell. This spell one-shots all npc except some warrior and spirit callers which i take care of afterwards.

In these 12 or so cycles, I've seen Grachnist once. When I was a lower level I came here while an SK was farming him and saw four up at the same time. I took a short break and a monk got 4 Grachnists to pop in 2-3 cycles.

As I was writing this he just popped, so that makes two. I am wondering if the game mechanics with regard to random numbers are working correctly. I understand that statistically someone who farms him is going to get two spawns in ~12 cycles, but it seems a little odd. My question is, are random numbers working properly with regard to respawning mobs that died at the same time and have the same spawn cycle? I could imagine a way in which this could have been programmed that would cause pbae casters to have terrible 'luck' with grachnist or any mob like it.

Thanks for reading.

EDIT: Update:

Did a few more rounds of the fort today, maybe 5 or 6. In total I saw 4 Grachnists and got my earring, so I'm out. The last round I actually killed in two parts by mistake, and that repop was the only time I saw more than one Grachnist up at a time. One of him spawned in the first half of the repops, and another in the second half. (Using track I could see what spawned in each group.) I still think this is bugged. Good luck.