first of all, it's sure that a well constructed URL is better for SEO (url with keywords)
What you can do, and what you seems to have done :
- keep the www.example.it/490/ URL for sharing,
- add a 301 redirection to your www.example.it/490/persons/jan-antone-vian when arriving in the first url (www.example.it/490/). The SEO juice should be transfered to the full url constructed.
Google says that ONE (and only one) URL has to be related to ONE (and only one) content, so you cannot let the both url displaying the same content. (you could be penalised for duplicate content...)
Note that a 301 is announced that it transfers the FULL SEO JUICE, but it's common to not do many 301 redirections in cascade.