Yes, they can. But since the only real prize of NaNoWriMo is the self-satisfaction that comes with pulling off such a great, creative feat, we don't really worry too much about people cheating. Those who enter an impossibly high number or send in 50,000 words they copied from Wikipedia.org just to see their name on the Winner's page are pitiful indeed, and likely need more help than a downloadable winner's certificate can provide them.
