Made the SuperModel a little bit more clever about handling duplicate loaded models.

app/models/SuperModel.coffee

@@ -119,7 +119,8 @@ module.exports = class SuperModel extends Backbone.Model
     for model, i in collection.models
       cachedModel = @getModelByURL(model.getURL())
       if cachedModel
-        collection.models[i] = cachedModel
+        clone = $.extend true, {}, model.attributes
+        cachedModel.set(clone, {silent: true})
       else
         @registerModel(model)
     collection

test/app/models/SuperModel.spec.coffee

@@ -50,3 +50,23 @@ describe 'SuperModel', ->
       _.defer ->
         expect(triggered).toBe(true)
         done()
+
+  describe 'collection loading', ->
+    it 'combines models which are fetched from multiple sources', ->
+      s = new SuperModel()
+
+      c1 = new ComponentsCollection()
+      c1.url = '/db/level.component?v=1'
+      s.loadCollection(c1, 'components')
+
+      c2 = new ComponentsCollection()
+      c2.url = '/db/level.component?v=2'
+      s.loadCollection(c2, 'components')
+
+      request = jasmine.Ajax.requests.sendResponses({
+        '/db/level.component?v=1': [{"_id":"id","name":"Something"}]
+        '/db/level.component?v=2': [{"_id":"id","description":"This is something"}]
+      })
+
+      expect(s.models['/db/level.component/id'].get('name')).toBe('Something')
+      expect(s.models['/db/level.component/id'].get('description')).toBe('This is something')