Backbone Collection with multiple models?

Create a base model that your other models inherit from:

var DataModel = Backbone.Model.extend({
    // Whatever you want in here
});

var FileModel = DataModel.extend({
    // Whatever you want in here
});

var FolderModel = DataModel.extend({
    // Whatever you want in here
});

And make the model type of the collection be that same base model:

var DataCollection = Backbone.Collection.extend({
    model: DataModel
});

You could also do it the backbone way. Check out the docs backbone collection

Basically you would create different models adding a tie breaker attribute say "type" in this case.

var file = Backbone.Model.extend({
        defaults: {
            // will need to include a tie breaker attribute in both models
            type: 'file'
        }
    }),
    folder = Backbone.Model.extend({
        defaults: {
            // tie breaker
            type: 'folder'
        }
    });

var fs = Backbone.Collection.extend({
    model: function(model, options) {
        switch(model.type) {
            case 'file':
                return new file(model, options);
            case 'folder':
                return new folder(model, options);
        }
    }
});

// after that just add models to the collection as always
new fs([
    {type: 'file',name: 'file.txt'},
    {type: 'folder',name: 'Documents'}
]);