Dear Raymond,
This is a use case that I am well aware of. Looking again at the mesh import code it looks a bit more messy than I hoped. The behavior actually depends on the mesh format:
1) In the ansys mesh (cdb file) import, which I had implemented myself, overlapping nodes are not removed at all (which I think is the most sensible thing to do).
2) In gmsh mesh import the default behavior is to merge overlapping nodes. In the C++ API the function import_mesh_gmsh() accepts a last optional argument that has to be set to false, to turn this behavior off. This option is currently not exposed in the Python API.
3) In the import of all other formats overlapping nodes are merged and the user cannot override this.
Which file format do you work with and do you use GetFEM through C++ or Python?
Best Regards
Kostas