Need to insert duplicate records in Entity Framework with list

Entity Framework he is doing his job correctly, the object services will find the duplicated items and insert them one time in db. Think about it! an entity represents a row in your table with an Id. You cannot insert the same row multiple times, you need a new primary key(Id).

You can clone your entity and add it to the DbContext or use this

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Example for Clone:

public class City
{
  [Key]
  [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
  public int Id { get; set; }

  public City Clone()
  {
    return (City)MemberwiseClone();
  }

}

public class MyDbContext : DbContext
{
  public MyDbContext(string connectionString)
        : base("name=" + connectionString)
  {
  }

  public DbSet<City> Cities { get; set; }
}

public static void Main(string[] args)
{
  Database.SetInitializer(new DropCreateDatabaseIfModelChanges<MyDbContext>());

  using (var myDbContext = new MyDbContext())
  {
    // This will add the city one time  => the bug
    var city = new City();

    var list = new List<City>();
    list.Add(city);
    list.Add(city);

    myDbContext.Cities.AddRange(list);
    myDbContext.SaveChanges();

    // This will add the city 2 times
    city = new City();
    var city2 = new City();

    list = new List<City>();
    list.Add(city);
    list.Add(city2);

    myDbContext.Cities.AddRange(list);
    myDbContext.SaveChanges();

    // This will add the clonned city1 and city=> Fix!
    var cityCloned1 = city.Clone();
    var cityCloned2 = city2.Clone();

    list = new List<City>();
    list.Add(cityCloned1);
    list.Add(cityCloned2);

    myDbContext.Cities.AddRange(list);
    myDbContext.SaveChanges();

  }

}

The result: