Indeed - this is VERY (very!) interesting. I have never seen that before. I can only assume it has once been a normal "moonbead" (with apertures in varying size, due to the shape of the rod used in the furnace-winding process) that have been drilled from both sizes in order to get same sized holes.

That lets me assume some hard tool - possibly a metal rod etc. - not a soft and flexible thread went into or through the hole. Likely for decoration purposes!

I have a theory (one I'd like to keep to myself for now) - one that may correlate with the original use of Lauschan marble beads, who were not meant to be jewelry neither!