using System;

using System.Collections.Generic;

using System.Linq;

​

namespace ConsoleApp1

{

    public class Program

    {

        public static void Main(string[] args)

        {

            List<Claim> currentClaims = new List<Claim>();

            currentClaims.Add(new Claim() { ID = 1 });

            List<Claim> newClaims = new List<Claim>();

            newClaims.Add(new Claim() { ID = 1 });

            newClaims.Add(new Claim() { ID = 2 });

​

            foreach (var newClaim in newClaims)

            {

                var existingClaim = currentClaims.FirstOrDefault(currentClaim => currentClaim.ID == newClaim.ID);

​

                if (existingClaim == null)

                {

                    //new claim

                    Console.WriteLine("Claim ID" + newClaim.ID + " is new");

                }

                else

                {

                    //use data from existing claim

                    Console.WriteLine("Claim ID" + existingClaim.ID + " is existing");                    

                }

            }

        }

    }

​

    class Claim

    {

        public int ID { get; set; }

    }

}

​