In order to be as flexible as possible, Doodle allows participants to choose any name during participation. One of your participants may have entered a fake name. Or maybe one of your participants inadvertently forwarded the link to another person, or published the URL on a public website.
As the admin, you can delete any vote in your poll. Simply hover your mouse over the name you wish to delete, and click on the trashcan icon next to the name. The vote cannot be restored.