c# – Distinct function not work properly

I want don’t show duplicate value but the Distinct() method show duplicate value also.
And I want don’t show null value also that’s why I use Where condition.

ViewData("TenderId") = new SelectList((from p in _context.TenderInfo
                                                   .Where(p => p.BankName != null)
                                                   select new
                                                   {
                                                       selectId = p.Id,
                                                       BankName = p.BankName
                                                   }), "selectId", "BankName").Distinct();

Look how duplicate value show