Navigadget spawning in inventory when entering caves

In RoG as Wheeler, left the navigadget inside Chester at camp. Entered a new sinkhole, and when I loaded in, an empty navigadget spawned in my pocket. When I went back to camp, the old navigadget was gone. Put it back in Chester and went to a different sinkhole that I had already been in before (cave had already generated). Navigadget entered my inventory again.
The first time I entered a cave in this world, I had Chester with me, with the navigadget in him.

Tested it again with a feather inside the navigadget, which was inside Chester; same result. Empty navigadget appeared in inventory when loading into a cave. However, the feather that was inside it appeared on the ground next to Chester upon returning to the surface. (Good to know it didn't eat whatever I had in there before...)

Edit: Dropped navigadget in caves last time it  poofed to me for lack of pocket space (surprising I know). It didn't re-add to my inventory on loading to the surface, and it is in fact still on the ground at my camp on the surface. Presumably the one dropped in the caves is still there as a duplicate.