If two sets of electors for a state representing two different candidiates provide their votes to Congress where the election results are contested then Congress will have to determine which set of votes was or was NOT submitted by electors elected in accordance with the laws of the state. They could accept one or the other, or reject both.
Submitting a competing set of votes by Trump electors guards against a situation where NO electoral votes are counted for a state if the Biden elector votes are discarded by the court or congress for fraud or other legal reasons and preserves the possibility that the President reaches 270 electoral votes without moving past this point and submitting the entire election to Congress to decide.
(If someone sees an error please post to reply.)
Complete without being over explain-y, thanks very much