Something weird happened in one of my recent games that I'd like to tell you and see if we can explain it somehow.

I was exploring GC around lvl 3 or 4 and a goblin wearing an arcanite chain mail and Vermis showed up in the mine field. I killed him and he was wearing an amulet of life saving so I had to kill him again. I took his items and kept on exploring the level. Nothing strange here as he probably found that stuff in the floor.

I found another amulet of life saving and another Vermis, so now I had two vermis, an arcanite chain mail and an amulet of life saving. I thought it was probably due to a wand of mirroring exploding somewhere as the amulet of life saving dissapeared within some minutes and the arcanite chain mail too. Now I cannot explain how both Vermis dissapeared and didn't found any other one in the whole level. Also I did not find the real arcanite chain mail either.

At least one Vermis shouldn't have dissapeared if it had been mirrored somehow. The AoLS I found could be the mirror image and the goblin used the real one, but I can't explain what happened with both Vermis and the arcanite chain mail.

Any idea what could have happened?

BDR is right, but for a bunch of items to spawn in pairs is rather odd however. I'm more inclined to think that a monster who picked up the vermis and chain mail stepped on a mine that had the amulet and a mirror wand nearby. Then the goblin came along (unless it wasn't killed, in which case it can be the goblin from the start) and picked up one of each.