Repating Data when fetch or duplicate data when application running in each time

I facing one issue , I store data in sqlite. I have two tablviewcontrollers. On First Tablviewcontroller will show types , & on that type selection will go to second table-view controller which shown name & date on that table-view controller, But i run application in any time it will fetch or repeat data of second table-view controller, e.g. on second tableviewcontroller have 2 rows data if i run application 2 time then it will reflect data on cell four time, same data repeat or duplicate. Using segue i pass data . Help me why this happen. Thanks.