The villagers that you revive can take another job.

If the revived villager has got another workstation that doesn't is his correspondent workstation, the villager takes it as a job but continues being of that job. Example:

A Librarian villager that you have trade with him before is killed by a zombie, you revive him without his lectern and instead of the lectern, you place another workstation. So, the villager will take that workstation as work and continues being Biblotecarian. 

https://youtu.be/NoJLTbjuw7Q A video where you can see that it really happens. If you relogin to the world the bug magically, fixes.