I'm trying to set up a simple parent-child object graph based on the example in the NHibernate docs.

I've managed to get a basic version working OK, but now I want to use the outer-join attribute to optimise the perfomance of the sql. However when I do this, I seem to be getting duplicate instances of my objects - e.g. if parent A has 2 child objects, I get 2 instances of A both with 2 identical children.

I'm new to this, so I'm probably missing something simple, but any advice is appreciated.