The truth: It's true that fraudulent registration forms do sometimes get submitted. What almost never happens is that an individual submits a form in someone else’s name in order to impersonate them at the polls. In most cases, it's a case of someone having a bit of fun, or making a mistake on their form, or voter registration workers, who typically work on commission, committing fraud.
Typical case: Says the Brennan Center report: "Most reports of registration fraud do not actually claim that the fraud happens so that ineligible people can vote at the polls. Indeed, we are aware of no recent substantiated case in which registration fraud has resulted in fraudulent votes being cast."