[Content Staging] Sync fails if you try to use the copy of an object

If you try to sync the copy of an object, the sync will fail with the following error:

Event synchronisation action results:
Object 123 to be synchronised to feed teste_sync: failure (HTTP error 404 (Not Found)) [Event 7]

Steps to Reproduce

1. Create and object - Object #001 - and publish it
2. Create another draft from Object #001.
3. Rename the new draft to Object #002 and publish the version 2
4. Create a copy of Object #002 and leave it with the same title
5. Try to sync
6. The object will be sync but won't be removed from the events and you will get an error every time you try to sync it

^{Note: This might be a regression from EZP-20537, maybe in 7aabe22983d4ad34da9c1056aeab874bb7565bae}