Clone of grouped shapes return incorrect size/position coordinates

[mszbot]

Problem: I have 2 grouped shapes on a slide. The right hand side grouped shape is a clone of the left, I simply copy-pasted it.

Reading the shape's size and position of the clone is incorrect. It provides the size and position of the left hand side grouped shapes.

Test template: Grouped.shapes.test.pptx

Expected result: All shapes should return the size and position as shown in PowerPoint GUI.

This is what the GUI shows for the chart shapes (inside the grouped shapes).

This is what python-pptx returns when you look up the size and position of all the shapes on this slide:

Shape ID: 9, Name: Group 8, Pos=(493.2, 128.88), Size=(428.96 x 342.21)
(Group contains:)
  Shape ID: 4, Name: Chart 3, Pos=(59.92, 200.16), Size=(474.32 x 301.17)
  Shape ID: 5, Name: TextBox 4, Pos=(135.36, 129.6), Size=(318.96 x 31.59)

Shape ID: 10, Name: Group 9, Pos=(71.92, 122.4), Size=(360.8 x 343.41)
(Group contains:)
  Shape ID: 11, Name: Chart 10, Pos=(59.92, 200.16), Size=(474.32 x 301.17)
  Shape ID: 12, Name: TextBox 11, Pos=(135.36, 129.6), Size=(318.96 x 31.48)

Notice shape ID 4 & 11 have the same size/position, as does shape ID 5 & 12.