Sinon mock not releasing binding after verify on test

collection_spec.js

// spec for tests on base Collection Class
describe("Moveline.App.Collection", function() {
	it("calls stageChangedModel when a collection model is updated", function() {
		var model = new Backbone.Model({
			'first_name': 'Chris',
			'last_name' : 'Allnutt'
		});
		
		var collection_mock = sinon.mock(Moveline.App.Collection.prototype).expects('stageChangedModel').once();
		
		var collection = new Moveline.App.Collection([model]);
		
		model.set({
			first_name: 'Lee',
			last_name: 'Hunter'
		});

		// verify method called on change
		expect(collection_mock.verify()).toEqual(true);
	});
	
	//FOLLOWING TEST THROWS ERROR BECAUSE MOCK CONDITION IS STILL BEING CHECKED AND BREAKING
	it("adds model to stagedModelChanges array when a collection model is updated", function() {
		var model = new Backbone.Model({
			'first_name': 'Chris',
			'last_name' : 'Allnutt'
		});
					
		var collection = new Moveline.App.Collection([model]);
		
		// set fires off a change event returning the model to it
		model.set({
			first_name: 'Fred',
			last_name: 'Cook'
		});

		// verify method called on change
		expect(collection.stagedModelChanges.length).toEqual(1);
	});
});