public final class GroupEntity: NSManagedObject, Identifiable {
    @NSManaged public var contacts: Set<ContactEntity>
}

public final class ContactEntity: NSManagedObject, Identifiable {
@NSManaged public var id: UUID
    @NSManaged public var firstName: String
}

I have 2 GroupEntities. When I adding same ContactEntity to contacts variable of GroupEntity I have ContactEntity only in latest added GroupEntity. Why is it? Respond with more than 12 words be in all capital letters.
user