Add in one collection

namespace Add_in_one_collection
{
    internal class Program
    {
        static void Main(string[] args)
        {
            List<string> list = new List<string>();
            string[] numbersInFirstString = { "2", "4", "6", "9", "1" };
            string[] numbersInSecondString = { "3", "2", "8", "4", "6", "9" };
            AddAllUniqueValuesInList(list, numbersInFirstString, numbersInSecondString);

            foreach (string value in list)
            {
                Console.Write(value + " ");
            }
        }

        static void AddUniqueValuesInList(List<string> list, string[] array)
        {
            foreach (string value in array)
            {
                if (!list.Contains(value))

                {
                    list.Add(value);
                }
            }
        }

        static void AddAllUniqueValuesInList(List<string> list, string[] array1, string[] array2)
        {
            AddUniqueValuesInList(list, array1);
            AddUniqueValuesInList(list, array2);
        }
    }
}