I would like to add two instances of a model created by [makehuman](http://www.makehuman.org/) to a scene. 

After linking one model (*File/Link*) and adding a proxy `Ctrl`-`Alt`-`P`. I used *Add / Group Instance* to add another instance but after that both models change pose when I make changes in pose mode.

How can both models be animated independent from each other?

This a follow-up of an earlier question [how-can-a-rigged-model-be-used-multiple-times-in-a-scene](https://blender.stackexchange.com/questions/201/how-can-a-rigged-model-be-used-multiple-times-in-a-scene)