Duplicating items in a list

// Create the list of items
var items = new List<Items>()
items.Add("Apple")
items.Add("Orange")

// This list will temporarily hold duplicates of the original items
var duplicates = new List<Items>();

// Loop through the original items and add each item to the list of duplicates
foreach (Items item in items)
{
    duplicates.Add(item);
}

// Loop through the duplicates and add the item back into the original list
foreach (Items item in duplicates)
{
    items.Add(card);
}

// Print each item
foreach (Items item in items)
{
    Console.Write($"{item}, ");
}

//Output
//"Apple, Orange, Apple, Orange, "