Illegal school budget vote?

I can't help but wonder just how legal the school budget vote actually was? When I went to vote, I saw the names & addresses of several people who sold their homes and moved out of Port years ago - so, why are they are still listed in the books as being able to currently vote in town? More importantly, I saw several of these names had "signed in" and somehow voted, despite not currently even being in the state, let alone town. Maybe from now on requiring a valid license or proof of ID when voting may make future votes just a bit more... legal?