Entities SaveChanges throws exception

Question

Im saving some locations/cities in my database. Thing is everything worked fine until i added one new column to the table in the database and updated the datamodel in my project.

My locations/cities DOES get saved althrough my this._entities.SaveChanges(); throws an execption that goes something like:

The changes to the database were committed successfully, but an error occurred while updating the object context. The ObjectContext might be in an inconsistent state. Inner exception message:AcceptChanges cannot continue because the object's key values conflict with another object in the ObjectStateManager. Make sure that the key values are unique before calling AcceptChanges.

I dont really know whats the problem since it worked before and this changes should not affect it really...

Here's some code:
First off i get all the objects into currentLocation. I loop them through a foreach to add item to method Add(). Last i call for _entites.SaveChanges(). Everything gets saved but i get an error...

           var webService = new WeatherWebService();
            currentLocation = webService.FindLocation(city);

            // ...save the user in the database.
            foreach (var item in currentLocation)
            {
                this._repository.Add(item);
            }

            this._repository.Save();

    public override void Add(Location location)
    {
        this._entities.Locations.AddObject(location);
    }

    public override void Save()
    {
        this._entities.SaveChanges();
    }

Answer 1

I suspect the exception may occur due to two different problems:

1- In previous calls, you have already retrieved locations; and you are trying to insert same values. 2- the primary key of location entities retrieved from web service are not unique.

In order to determine the exact problem, please check inner exceptions of the displayed exception.