The Item Level Versioning creates version numbers, that are used to mint Persistent Identifiers. G.e. if a new Item gets the handle 123456/100 all new version of the item get the handle 123456/100.x with x = the version number. The second version will get the handle 123456/100.2, the third 123456/100.3 and so on. This behavior is described in
DS-1348, DS-2490 and DS-2496.
When a version gets deleted DSpace currently deletes the information that the version ever existed. This may lead to a reuse of a Persistent Identifier that was already used for a previously deleted version.
G.e.: An Item is created and get the handle 123456/100. Its second version would get the handler 123456/100.2. If the seconds version gets deleted and a new version is created it will get the version number two again and the handler 123456/100.2 which was used for another version before. DSpace should keep the version number persistent to avoid such a situation. A solution would be to set the item_id in the table versionitem null when a version is deleted instead of deleting the complete information that this version ever existed.