This is the only example of a 'Double Pumpkin' I've ever seen.  By Double Pumpkin, I mean that there are two pumpkin floats that are roped together in their original netting.

One pumpkin has one patch or dab of glass attached to the float.  The other pumpkin has three patches.

There is a disc of rubber between the two floats, so the two glass floats don't actual touch each other.  It appears to be made out of something like a piece of tire.

The ropes are quite interesting.  They look to be of very poor quality.  I've seen a few pumpkins with their original nets and this netting appears to be quite similar. 

I think this helps explain why these floats got away from the fishermen.  The rope is of such low quality that these pumpkin floats wouldn't remain secured for long in the rigors of ocean fishing.

Love this unique configuration and use of pumpkin floats.

Found on Hokkaido Island, Japan.