Could you give some more details on what is merged, and how? Maybe an example, with translations, and versions?
Update: from the README on GitHub (answering some of my query)
Merge will copy selected content translations from the different attributes to the master content object ("Merge to..." column). This will be done by adding a new version on the master. It will use the builtin toString()/fromString() functionality for the copying.
For attributes of the object relation list datatype it will merge the relations from the two objects into the master (sort order will be master relations first, then slave relations).
Any reverse related objects will be updated to relate to the master object instead of the slave. This supports attributes of the object relation list datatype, single object relations, and XML fields. The children of any slave nodes will be moved to the master main node.
Each translation from the two objects will be created on the master object.
The slave object will be removed after the merge.
The merge does not support url alias history. When slave object is merged into master, url aliases should be updated to forward any urls to the master object.