When a Warlock casts an Animus, is it still an Animus?
A model can have only one friendly animus in play on it at time. If another friendly animus is cast on a model, th eolder friendly animus expires and is replaced by the new one when the affected model is hit by the animus. This applies to animi used by warbeasts as well as those cast as spell. 
cit from the quickstart rules pag 4 right column ANIMI block. 

To answer your question your friend is right :)