Share VBO across Meshes

How could I share VBO across mesh?

By setting the same material to multiple renderer, I allow Unity to dynamicly batch my draw call. Nice.

But, even if I instanciate the same prefab, my VBO count is going throught the roof : for 9 objetc one draw call but 9 VBO.

I've tried to set as the sharedMesh of my instanciate object the shared mesh of a "prefab zero" Instancated at start but doesn't seems to care : it still show me 9 VBO in the stat window...

Is there a mean to share the same VBO when the mesh is the same? A bit stupid to create new VBO when only the world matrix change : /