Here are 2 methods.
Both are using random rotation to add directional variation, which allows you to use more subtle variation between clones.
Method 1 uses a displacer to create bumpiness. the texture space of the noise is set to texture…meaning each clone gets the same displacement.
The random rotation covers a lot of the repetition up.
method 2 uses the cloner in blend mode to blend between 2 deformed states.
Again this creates something that is fairly regular at first…so you want to add in the random rotation to break up the effect.
This is just a starting point, and you could also create a mash up of the 2 methods if you like.