Hi Bart,
One of the advantages of Linked Duplicates is, that you can Transform them in Object Mode to make them look slightly different. You can also use different Modifiers on the Copies. They all use the same ‘list’ of Vertex Positions, but the can use different Coordinate Systems.
Here, for instance, are 3 Linked Default Cubes:

If you, however, make any changes in Edit Mode, you change the Position of the Vertices and that will make changes in all Linked Duplicates.