children panel not updated

  1. add a duplicate layer,
  2. go to children panel, select the index value
  3. delete the duplicate
  4. the index value is still in children panel

is this a feature or a bug?

It is a feature. Exported value nodes aren’t’ remove if the layer is removed. It happens in any case of layer.
To remove a exported value node you need to “Unexport” it.