In RAT FRAUD centers, partisan RATS mark Trump ballots with a mark for Biden also so the vote machine rejects them and they go to adjudication. The adjudicators consists of only partition RATS who award those ballots to Biden. That is how a lot of the fraud occurred. It is why the adjudication rates skyrocketed in 2020 from historical norms.
Note: This fraud technique was premeditated and shared at a national level. It WAS NOT something that some sneaky RAT thought up in some isolated district on election day.