Reply To: Plank all separate unique versions on top.

Linking Onject Data means, that all those Linked Objects share the same ‘list’ of where Vertices are in the Object’s own Coordinate Systems:

Changing a Vertex in 1 of those Objects, changes it in all. You can Transform (Move, Scale, Rotate) each Object to get different looks, although the Objects are sharing the same Data, to vary the look of each Instance/ Linked Duplicate.

Using SHIFT+D Duplicates is just an awful lot of extra modeling work and with Linked Duplicates, you can still get loads of variation. 

As a proof of that, this Scene only uses 5 different planks: https://cgcookie.com/projects/nelson-s-blood