In general these interfaces and methods are good to implement when working with comparing objects of the same type in C#:

Interfaces:
System.IEquatable<T> – strongly typed implementation
IComparable<T> – strongly typed implementation

Override methods:
An override of Object.Equals(Object).
An override of Object.GetHashCode().
An override of Object.ToString() is usually a good idea.
Operator overloads for operator == and operator !=.

General rule of GetHashCode():
If two objects is equal then their hashvalues should be the same.
E.g.:
If Equals == true then
x.GetHashCode() == y.GetHashCode()
GetHashCode() is frequently used by collections like Dictionary<Key, Value> and HashSet<T>

Links:
Guidelines for Overloading Equals() and Operator == (C# Programming Guide)
https://msdn.microsoft.com/en-us/library/ms173147.aspx

• How to best implement Equals for custom types?
  http://stackoverflow.com/questions/567642
• Implement value objects
  https://docs.microsoft.com/en-us/dotnet/architecture/microservices/microservice-ddd-cqrspatterns/implement-value-objects
• C# – Always valid value objects
  https://danielwertheim.se/csharp-always-valid-value-objects/
• What is the best algorithm for overriding GetHashCode?
  https://stackoverflow.com/questions/263400

EDIT: This is now part of MoreLINQ.
What you need is a “distinct-by” effectively. I don’t believe it’s part of LINQ as it stands, although it’s fairly easy to write:

public static class EnumerableExtensions
{
public static IEnumerable<TSource> DistinctBy<TSource, TKey>(this IEnumerable<TSource> source, Func<TSource, TKey> keySelector)
{
HashSet<TKey> seenKeys = new HashSet<TKey>();
foreach (TSource element in source)
{
if (seenKeys.Add(keySelector(element)))
{
yield return element;
}
}
}
}

Source: c# – LINQ’s Distinct() on a particular property – Stack Overflow