Item title is full front title, this is why the site has entries like that. If we use a simple rule as this, we don't have to worry about exceptions.
So for the example you put:
name: DreamWorks Rise of the Guardians
fan-name: Rise of the Guardians
The reason why that is the fan name "because no one calls it DreamWorks Rise of the Guardians" and we can apply this logic to Disney/Pixar/whatever games (as you see in the ref threads) meaning these popular ways of referencing games are fan names and not official.
We know obviously that they have DreamWorks there as an advertisement for the studio, because there may exist people who see or buy that game and not know it is from a movie... BUT it doesn't change the fact that when they designed that packaging, they put the company name into the logo.
In the case of the example above, "Rise of the Guardians" would not need to be put into alt-name field because it is already in the title.
Reference:
https://vgcollect.com/forum/index.php/topic,4715.0.html