Equality.cs

//Implement IEquatable<> interface and have these methods below

public bool Equals(User other)
    {
        return IsEqual(other);
    }


public override bool Equals(Object obj)
{
    //Check for null and compare run-time types.
    if ((obj == null) || !this.GetType().Equals(obj.GetType()))
    {
        return false;
    }
    else
    {
        User model = (User)obj;
        return IsEqual(model);
    }
}

private bool IsEqual(User other)
{
    if (this.UserID == other.UserID)
    {
        return true;
    }
    else
    {
        return this.EmailAddress == other.EmailAddress;
    }
}