Problems creating delaunay with C#

i want to create a Delaunay mesh from a point cloud with C#. The problem is actually quite easy since the point cloud is almost flat (xy plane). Nevertheless, I get an invalid mesh with holes and overlaps.

I attached the file here: (13.5 KB)
Am I missing something stupid? As far as I understood, jitter should be set to 0 for this type of problem.

Duplicate points:

You can cull such points inside C Sharp by adding points XYZ coordinates to a HashSet as strings.

Don’t forget if duplicates of the points are culled, the numbers should also be culled.

Thank you!