The number of triangles drawn you see includes additional draws of the mesh, like dynamic shadows and probably occlusion queries too. It does not mean that mesh is drawn twice in 4.15 so essentially there might be nothing to fix.
Actually,I’m trying to update my 4.13 project to 4.15. In 4.15, the frame rate is lower than 4.13. And GPU Visualizer shows that BasePass takes more times. So I did this test to find the reason.
The scene is the same and the light has been built. What can I do to optimize it?