The way meshes are stored in memory

Hi, while working in a simple level of detail system, i came to an elemental question.
‘How does blender stores the meshes of the objects when they’re in the scene?’
I mean, if i have a house prop, with his mesh, and place linked houses in the scene, will it store in memory the mesh (not the object) once? or will it load ‘different’ meshes that are actually the same for each linked group?
The reason i ask this is that if it indeed loads a buch of equal meshes, then i prefer to import the mesh once, and then by code, tell each prop to change his mesh to that only one.