vtkCleanPolyData and vtkStaticCleanPolyData obviously process polydata.
For other subclasses of vtkPointSet such as unstructured grids similar filters could be written. However, we need to define a bunch of degeneracies: e.g., what happens when the points of a hexahedron are merged, depending on which points/how many, you could end up with a whole host of frankenstein cells. And it gets worse with higher order cells and such. If you want to create a specialized filter that just merges points and doesn’t change cell type, this is easy to do. We’d love to see an MR appear 