Union of polygons with coinciding sides

[dh-s]

After further thought (and receiving no comments/answers here), I have raised this as an issue (#970) and will close this discussion.

I was expecting that polygons with coinciding sides would be combined into a single polygon by a union. This is what I am seeing is some examples, but not in others.
In the example below I have used Clipper2 to union the 2 sets of 3 polygons that are shown in white - the results (which I have moved so they don't overlap the originals) are in red (and are as I expected for the polygons on the left, but not for those on the right).

Is it incorrect of me to expect the union of the polygons on the right to produce a single resulting polygon in the solution?

Delphi code to reproduce the union of the polygons on the right is as follows:
`

var plys : TPaths64;

setlength (plys, 3, 4);

Plys[0][0].X := 107373296816202;
Plys[0][0].Y := 44392781971456;
Plys[0][1].X := 105449517812064;
Plys[0][1].Y := 45845000865118;
Plys[0][2].X := 105501899139659;
Plys[0][2].Y := 43461386037664;
Plys[0][3].X := 107425678143797;
Plys[0][3].Y := 42009167144002;
Plys[1][0].X := 108790761145585;
Plys[1][0].Y := 42786050594804;
Plys[1][1].X := 107373296816202;   // the side between points 1 and 2 in 
Plys[1][1].Y := 44392781971456;    // plys[1] coincides exactly with the
Plys[1][2].X := 107425678143797;   // side between points 3 and 0 in plys[0]
Plys[1][2].Y := 42009167144002;    // (in opposite direction)
Plys[1][3].X := 108843142473179;
Plys[1][3].Y := 40402435767349;
Plys[2][0].X := 109658841863835;
Plys[2][0].Y := 41073626454996;
Plys[2][1].X := 108790761145585;   // the side between points 1 and 2 in
Plys[2][1].Y := 42786050594804;    // plys[2] coincides exactly with the
Plys[2][2].X := 108843142473179;   // side between points 3 and 0 in plys[1]
Plys[2][2].Y := 40402435767349;    // (in opposite direction)
Plys[2][3].X := 109711223191430;
Plys[2][3].Y := 38690011627542;

var sol : TPaths64;

var Clipper := TClipper.Create;
try
  Clipper.AddSubject ( plys);
  Clipper.Execute(ctUnion, l^.fillRule, sol);
finally
  Clipper.Free;
end;

var sol : TPaths64;

var Clipper := TClipper.Create;
try
  Clipper.AddSubject ( plys);
  Clipper.Execute(ctUnion, frNonZero, sol);
finally
  Clipper.Free;
end;`

[dh-s]

I have raised this as an issue, so the discussion is no longer relevant