Here is the html for the date field :
Using this datepicker I had the same problem. I solved it using a little trick.
In the inputs tag I added a new attribute (dp-model):
...
And then in the js file I forced the binding in this way:
$scope.formData.dp = []; // arrays of yours datepicker models
$('.dp').datepicker().on('changeDate', function(ev){
$scope.formData.dp[$(ev.target).attr('dp-model')] = $(ev.target).val();
});