Is this expected behaviour for a difference operation?

[DavinLunzKodiak]

Hi, I'm new in town. I have the following case:

CLIPTYPE: DIFFERENCE
FILLRULE: NONZERO
SUBJECTS
0,0 2,0 2,3 0,3
2,0 4,0 4,3 2,3
CLIPS
1,1 3,1 3,2 1,2
3,1 5,1 5,2 3,2

Two adjacent rectangles (blue) and two adjacent clips to remove (red):

The result is two polygons (green):
2,1 1,1 1,2 2,2 3,2 4,2 4,3 2,3 0,3 0,0 2,0
4,1 3,1 2,1 2,0 4,0

At first glance, this appears surprising. The original two polygons have been merged above the clip, but left separate below. If there are unions happening under the hood, I would have expected to get a single polygon comprising the union of the two green polygons. If there are no unions happening under the hood, I would then expect to get three polygons. But to get two polygons means that there are sometimes unions happening?! Is this expected? Thanks for any explanation.

[AngusJohnson]

Thanks David.
Yes, I guess it is a bug of sorts, though a very minor one.
I've fixed it in the latest Repository commit, but merging of adjacent touching edges won't happen if the edges are extremely short (as is in the sample above). Merging of touching polygons should happen as expected if you scale the above polygons (eg by a factor of 10).