Not having seen the movie yet, but am willing to believe that this is similar to how David Gerrold came up with tribbles that were amazingly like Heinlien's "flat cats" from The Rolling Stones. Possible subconscious influence, but primarily an independent derivation of someone exploring the same kind of questions about identity.
I will see Avatar, but I have to say I think Anderson is already one up with me. He crafted a very memorable story without the artificial addition of an action adventure war.