Hello Rodrigo Punk,
Thank you for using our services.
You can set the poll box to show a results link even if the user has not voted (see attached images). If this is what you mean, then yes there is out of the box functionality. If however you are asking whether there is the functionality to check user names instead of IP for allowing users to vote, I am afraid that my answer would be no. This is not available.
I hope that this would answer your question. If you feel that you need more assistance on working with Sitefinity, feel free to contact us.
the Telerik team