Any way to suppress Hibernate "More than one row with the given identifier" exception?

Question

In our domain model, one Event is designed to have zero or one Notification, so I started to use @OneToOne annotation for entity relation:

class Event {
...
    @OneToOne(mappedBy = "event")
    Notification notification;

In most cases it works fine, but in very rare cases there are duplicate Notifications for a single Event, which differ only by milliseconds in timestamp. If such happens, Hibernate throws an exception:

javax.persistence.PersistenceException: org.hibernate.HibernateException: More than one row with the given identifier was found: 1290338, for class: Xxx

-- and the entire result set fails.

The workaround I implemented: annotate relation as @OneToMany but return a single Notification through a getter:

@OneToMany(mappedBy = "event")
List<Notification> notifications;
...

public Notification getNotification() {
    return notifications == null || notifications.isEmpty()
           ? null : notifications.get(0);
}

It works pretty fine, but the thing I dislike here is that bean style of class is broken. My question: is there Hibernate preference to suppress mentioned exception, so I can manage without custom getter?

Database is managed and populated by outer system, so there is no possibility to add constraint nor control insertion of duplicates.