It might be helpful,
class Program
{
static void Main(string[] args)
{
List<string> listOne = new List<string>() { "listTwo_1", "listTwo_1", "listOne_3", "listTwo_1" };
List<string> listTwo = new List<string>() { "listTwo_1", "listTwo_2", "listTwo_3", "listTwo_1" };
Common(listOne, listTwo).ForEach(item => Console.WriteLine(item));
}
static List<string> Common(List<string> first, List<string> second)
{
return first.Where(item => second.Contains(item)).Distinct().ToList<string>();
}
}
:)