duplicate object if there is region overlap?

[redfood]

If regions overlap and you listed for two regions you get the same blob twice - once for each region (I think).

It probably would be better if every blob had an id, there was a list of all the blobs with their ID, and then a region would just contain lists of blob IDs.

Why would this be better (1) it should be more compact (2) can tell if a blob is in a region of overlap so you don't react to it twice.

(Additionally - it would be great if each blob also had a list of the regions with witch it overlaps).