Violation of PRIMARY KEY constraint.. hjälp med problem

public class ApplicationUser : IdentityUser
    {
        public Symptom Symptom { get; set; }

        [Required]
        public byte SymptomId { get; set; }

        [Required]
        public string Telephone { get; set; }

        public string Descripton { get; set; }
    }

public class Symptom
    {
        public byte Id { get; set; }

        [Required]
        [StringLength(255)]
        public string Name { get; set; }
    }

    public partial class UpdateUserTblAddSymptom : DbMigration
    {
        public override void Up()
        {
            AddColumn("dbo.AspNetUsers", "SymptomId", c => c.Byte());
            CreateIndex("dbo.AspNetUsers", "SymptomId");
            AddForeignKey("dbo.AspNetUsers", "SymptomId", "dbo.Symptoms", "Id", cascadeDelete: true);
        }
        
        public override void Down()
        {
            DropForeignKey("dbo.AspNetUsers", "SymptomId", "dbo.Symptoms");
            DropIndex("dbo.AspNetUsers", new[] { "SymptomId" });
            DropColumn("dbo.AspNetUsers", "SymptomId");
        }
    }

public partial class PopulateSymptomTable : DbMigration
    {
        public override void Up()
        {
            Sql("INSERT INTO Symptoms (Id, Name) VALUES (1, 'Affektiva störningar')");
            Sql("INSERT INTO Symptoms (Id, Name) VALUES (2, 'Psykossjukdomar')");
            Sql("INSERT INTO Symptoms (Id, Name) VALUES (3, 'Ångestsjukdomar')");
            Sql("INSERT INTO Symptoms (Id, Name) VALUES (4, 'Ätstörningar')");
            Sql("INSERT INTO Symptoms (Id, Name) VALUES (5, 'Beroende och substansrelaterade sjukdomar')");
            Sql("INSERT INTO Symptoms (Id, Name) VALUES (6, 'Sexualitet och sexuella störningar')");
            Sql("INSERT INTO Symptoms (Id, Name) VALUES (7, 'Somatoforma och psykosomatiska sjukdomar')");
            Sql("INSERT INTO Symptoms (Id, Name) VALUES (8, 'Personlighetsstörningar')");
            Sql("INSERT INTO Symptoms (Id, Name) VALUES (9, 'Neuropsykiatriskt funktionshinder')");
        }

        public override void Down()
        {
            Sql("DELETE FROM Symptoms WHERE Id IN (1, 2, 3, 4, 5, 6, 7, 8, 9)");
        }
    }

Violation of PRIMARY KEY constraint 'PK_dbo.Symptoms'. Cannot insert duplicate key in object 'dbo.Symptoms'. The duplicate key value is (5).
The statement has been terminated.

//
        // POST: /Account/Register
        [HttpPost]
        [AllowAnonymous]
        [ValidateAntiForgeryToken]
        public async Task<ActionResult> Register(RegisterViewModel model)
        {
            var symptom = _context.Symptoms.Single(s => s.Id == model.Symptom);
            //var status = _context.Statuses.Single(s => s.Id == model.Status);

            if (ModelState.IsValid)
            {
                var user = new ApplicationUser()
                {
                    UserName = model.UserName,
                    Telephone = model.Telephone,
                    Symptom = symptom,
                    //Status = status,
                    Descripton = model.Descripton
                };

                HÄR KRASCHAR KODEN!
                var result = await UserManager.CreateAsync(user, model.Password);
               

 if (result.Succeeded)
                {
                    await SignInAsync(user, isPersistent: false);
                    return RedirectToAction("Index", "Home");
                }
                else
                {
                    AddErrors(result);
                }
            }

            // If we got this far, something failed, redisplay form
            return View(model);
        }

var userId = User.Identity.GetUserId();

            var loggedInUser = (_context.Users
                .SingleOrDefault(u => u.Id == userId));

            var applicationUsers = _context.Users
                    .Where(u => u.StatusId == (byte)AvailableStatus.Available
                        && u.SymptomId == loggedInUser.SymptomId)
                    .Include(s => s.Symptom)
                    .Include(s => s.Status)
                    .ToList();

            var randomUser = applicationUsers[(new Random()).Next(applicationUsers.Count())];

            return View(randomUser);

var loggedInUser = (_context.Users
                .SingleOrDefault(u => u.Id == userId));

            var applicationUsers = _context.Users
                    .Where(u => u.StatusId == (byte)AvailableStatus.Available
                        && u.SymptomId == loggedInUser.SymptomId)
                    .Include(s => s.Symptom)
                    .Include(s => s.Status)
                    .ToList();

            var applicationUsers = _context.Users
                    .Where(u => u.StatusId == (byte)AvailableStatus.Available
                        && u.SymptomId == _context.Users.Where(iu => iu.Id == userId).Select(iu => iu.SympthomId).FirstOrDefault())
                    .Include(s => s.Symptom)
                    .Include(s => s.Status)
                    .ToList();

var loggedInUser = applicationUsers.SingleOrDefault(u => u.Id == userId));

var applicationUsers = _context.Users
    .Where(u => 
        u.StatusId == (byte)AvailableStatus.Available && 
        u.Symptom.Users.Any(iu => iu.Id == userId))
    .Include(s => s.Symptom)
    .Include(s => s.Status)
    .ToList();

var loggedInUser = applicationUsers.SingleOrDefault(u => u.Id == userId));