Comparing independently by Id value and by property values

Question

I am working with an abstract class RepositoryItemBase as follows:

public abstract class RepositoryItemBase : ICloneable, IEquatable<Dto>
{
    protected internal Guid Id => Guid.NewGuid();

    protected RepositoryItemBase() { }

    public object Clone()
    {
        return MemberwiseClone();
    }

    public bool Equals(Dto other)
    {
        //??
    }
}

Since the intention is to save it to a repository, I made the following design choices:

1. When I call repo.Save(repoItem), I want the item to be cloned upon saving, so that I can keep editing it without changing the stored reference, until I call repo.Save(repoItem) again;
2. If I call Save with an item with same Id but different property values, I want it to call the private repo.Update(repoItem);
3. If I call Save and a stored item with same Id also has the same property values, the method returns immediately witout actually persisting anything;

My questions are:

• Are there common C#/.Net idioms / interfaces to differentiate an Id-based comparison and a property-value-based comparison? I would like to independently perform these two types of comparison.

• Is IEquatable the best interface to implement?

• Does .Net have some sort of IIdentifiable or IIdentity interface, with a Guid Id { get; } property or something like that?