pick a random records from a datatable

I'm trying to pick n records randomly from a datatable and tag them as winners. according to THIS POST i need to "choose an item by index from a source list at random (which i dont know how to do that) , remove it from the source list as you go, and putting it on the destination list" like dt2. now there is a problem there because the dt or my datatable has duplicated records and they all have to be there unless 1 of them was picked (that means if a duplicate record popped out once, all the records with the same "IC NUMBER" should be removed from dt but the dt2 should now have a new record of that person). how can i do this?