The document says, The store auto-loads a set of User model instances from the URL users.json. So can a store have multiple model instances? How do I tell the store which model instance to be used from the collection of model instances?
or "can a store work with more than one different model class?"
The answer the q1 is a simple yes, look at the API for stores, such as getAt(index) etc.
The answer for q2 is probably no. You might have some luck extending 2 model classes from a base class and then using the base class with the store, maybe it will accept instances of the sub class models, but I'm not sure.