how do I stop a loop on a method from repeating the same values on its drop down list after it has gone through its regular loop the first time? Example my dropdown list has 4 values after the loop, if I select it again I will have the same 4 values repeated making it 8 values in total. I only want the original 4 values in my drop down list to stay 4. What code do I need to insert to prevent it from duplicating again. C# window application