Item c = (Item) hibernateSession.load(Item.class, ItemPk);

c.set...();
c.set...();
c.set...();

tx = hibernateSession.beginTransaction();
hibernateSession.save(il);
tx.commit();

This fails with "identifier of an instance of Item was altered from ItemPk..."

And that's what I actually want to do... I want to fetch an existing record from the DB, modify some of it's values, and insert it as a new one.

How could I do that with hibernate?

The instance is "connected" to the hibernateSession. Call evict() to detache the entity and set the identifier to null. After that call save().

Thanks, that worked beautifully

And how can I evict an object that is not connected to the session, that is, it's used by other session but it has undesired identifier from the first session?