Putting the name of the “other” party on fake registrations would be smart cover for the move if caught. Whatever the registrations I believe that if enough ballots are thrown out to be more than the margin of victory then all they can maybe rerun the election. Tainting only one candidate with rejected secret ballots may be an act just as corrupt as the false registrations.
Democrats vote in Republican primaries to nominated the weaker candidate. Happens all the time. That’s how Missouri got Todd “Rape Rape” Aiken.