Hibernate seems to have an issue under the following scenario with the following simple mappings (all lazy)

• * Parent -> OneToMany -> Child
• Child -> ManyToOne -> Parent

1. Enable batch fetching
2. Read in Parent1 and a (non-related) Child
3. Lock and refresh the original Parent1 / this will prompt a batch fetch of the other child's ParentX
   1. At this time, it appears the original Parent1 is "duplicated" in the session cache
4. Directly read in a Child associated with Parent1
5. Refresh the original reference to Parent1 causing Hibernate to now directly see two Parent1s in the cache
6. Flush the session

Note I believe this issue is also related to HHH-12268 Open which still also exists in the latest 5.x versions.