Entity Framework Seeding with Identity (Microsoft.Owin.Security) user

I have a class that seed the database which add 2 users with roles and custom fields. The problem I have is that it save the data in [dbo].[AspNetUsers] instead of [dbo].[IdentityUsers]. Both tables are created. When seeded, the data go into AspNetUser. When I launch the web site, and register a new user, the data go into IdentityUser.

Here is the Migration class :

internal sealed class Configuration : DbMigrationsConfiguration<DatabaseContext>
{
    public Configuration()
    {
        AutomaticMigrationsEnabled = true;
    }

    protected override void Seed(DatabaseContext context)
    {
        base.Seed(context);

        var userStore = new UserStore<ApplicationUser>();
        var manager = new UserManager<ApplicationUser>(userStore);

        var role = new IdentityUserRole { Role = new IdentityRole(Model.Roles.ADMINISTRATOR) };
        var user = new ApplicationUser() { UserName = "123123", Email = "123123@123.com", Language = "en-US"};
        user.Roles.Add(role);
        IdentityResult result = manager.Create(user, "123123");

        var role2 = new IdentityUserRole { Role = new IdentityRole(Model.Roles.NORMAL) };
        var user2 = new ApplicationUser() { UserName = "qweqwe", Email = "qweqwe@qweqwe.com", Language = "fr-CA" };
        user.Roles.Add(role2);
        IdentityResult result2 = manager.Create(user2, "qweqwe");
    }
}

Here is the ApplicationUser class which define custom field for the Identity model.

public class ApplicationUser : IdentityUser, ICurrentUser
{
    public ApplicationUser()
    {
        Email = "";
        Language = "";
    }
    public string UserId {
        get { return base.Id; }
        set{} 
    }
    public string Email { get; set; } 
    public string Language { get; set; } 

}

Here is the Entity Framework configuration class for this new class.

public class ApplicationUserConfiguration : EntityTypeConfiguration<ApplicationUser>
{
    public ApplicationUserConfiguration()
    {
        this.HasKey(d => d.Id);
        this.Ignore(d => d.UserId);
    }
}

Both are using the save DataContext with the same configuration:

 protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        base.OnModelCreating(modelBuilder);

        //... others entity here

        modelBuilder.Configurations.Add(new ApplicationUserConfiguration());

        //Theses configuration are required since custom fields are added to ApplicationUser. Here is why : http://stackoverflow.com/questions/19474662/map-tables-using-fluent-api-in-asp-net-mvc5-ef6
        modelBuilder.Entity<IdentityUserLogin>().HasKey(l => l.UserId);
        modelBuilder.Entity<IdentityRole>().HasKey(r => r.Id);
        modelBuilder.Entity<IdentityUserRole>().HasKey(r => new { r.RoleId, r.UserId });

    }

My question are: Why do I have AspNet prefixe tables name that is duplicated from Identity tables? Why does the seed use one while the web application use the other?