Assert.Equivalent fails with ArgumentException ("An item with the same key has already been added.") when baseclass uses "new" on property

[Joost-Jens-Luminis]

When a subclass overwrites a parent's class property with a more specific type, Assert.Equivalent fails with the following exception:
System.ArgumentException : An item with the same key has already been added. Key: ID

This appears to go wrong in AssertHelper.cs here:

The following example shows the issue:

[Fact]
public void TestMyClass()
{
    MyClass c1 = new MyClass("123");
    MyClass c2 = new MyClass("123");

    Assert.Equivalent(c1, c2);
}

public abstract class MyDomainBase<T>
    where T : MyDomainBase<T>
{
    protected MyDomainBase(object id)
    {
        ID = id;
    }

    public object ID { get; }
}

public abstract class MyDomainBase<T, TIdentifier> : MyDomainBase<T>
    where T : MyDomainBase<T, TIdentifier>
{
    protected MyDomainBase(TIdentifier id) : base(id)
    {
        ID = id;
    }

    public new TIdentifier ID { get; }
}

public class MyClass : MyDomainBase<MyClass, string>
{
    public MyClass(string id) : base(id)
    {
    }
}

Edit; styling and formatting.

[Joost-Jens-Luminis]

Replacing the code part I meantioned above in AssertHelper with the following changes seem to fix the issue:

  return
      fieldGetters
          .Concat(propertyGetters)
          .GroupBy(g=> g.name)
          .ToDictionary(g => g.Key, g => g.First().getter);