[vtkusers] vtkExtractSelectedFrustum introduces duplicate nodes

[kshivann at engineering.uiowa.edu]

hi all,
    i am using vtkExtractSelectedFrustum to select portion of a mesh.  
The extracted mesh has duplicate nodes. The piece of code is as follows

	vtkExtractSelectedFrustum *Extract = vtkExtractSelectedFrustum::New();
	Extract->SetInput(this->PreviousSelectedSubset);
	Extract->PassThroughOn();
	Extract->SetFrustum(AreaPicker->GetFrustum());
	Extract->Update();

I am not sure why would the filter introduce duplicate nodes.

thanks

Kiran