title: The instance of entity type cannot be tracked because another instance with the same key value for is already being tracked
body: <blockquote>
  <p>The instance of entity type 'AssegnazioneLotto' cannot be tracked
  because another instance with the same key value for
  {'Id_AssegnazioneLotto'} is already being tracked.</p>
  <p>When attaching existing entities, ensure that only one entity instance
  with a given key value is attached.</p>
  <p>Consider using 'DbContextOptionsBuilder.EnableSensitiveDataLogging'
  to see the conflicting key values.</p>
  </blockquote>
  <p>I encounter this error when we call data from a table and update it.</p>
  <p>I solved it by calling a view which calls the table.
  Why does this happen?
  How can I solve without creating additional views?</p>