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CSharp · Console

/Program.cs

using System;
using System.Collections.Generic;
using System.Linq;
					
public class Program
{
	public static void Main()
	{
		Thing unique1 = new Thing("test", 1);
		Thing unique2 = new Thing("test1", 1);
		Thing unique3 = new Thing("test", 2);
		Thing dup1 = new Thing("test", 1);
		Thing dup2 = new Thing("test", 1);
	
		Thing[] things = {
			unique1,
			unique2,
			unique3,
			dup1,
			dup2
		};
	
		List<Thing> duplicateThings = 
			things
				.GroupBy(thing => new { thing.Name, thing.ServiceGroup })
				.Where(group => group.Count() > 1)
				.SelectMany(group => group.ToList())
				.ToList();
			
		foreach(Thing thing in duplicateThings)
		{
			Console.WriteLine("{0}:{1}", thing.Name, thing.ServiceGroup);
		}
	}
	
	public class Thing
	{
		public string Name { get; set; }
		public int ServiceGroup { get; set; }
	
		public Thing(string name, int serviceGroup)
		{
			this.Name = name;
			this.ServiceGroup = serviceGroup;
		}
	
		public Thing()
		{
	
		}
	}
}