I built the Spring 2.5.6 PetClinic application pretty much out of the box, configured with Hibernate's JPA implementation, binding to MySQL.

When I execute any operation in the UI that inserts a new object, it always creates two duplicate objects, as if I created it twice. This happens for all the domain objects. When the page redisplays, it shows two copies of each object that I created (not the existing ones).

I then reconfigured the application to just use plain Hibernate, not JPA, and it does not display the symptom.

I set a breakpoint on the "Owner.addPet()" method, and it only hits it once.

What else can I do to narrow this down, if no one has a quick answer for me?