I thought it was already determined that Biden won with 302 votes and the election was put to bed... as in done.
Both of them have enough votes to win an this point. The question is now, which votes are going to be counted?
VP Pence counts the votes, in the presence of both houses of Congress. Getting two sets of votes from a state is not a new thing. It happened when Hayes was elected—three states each sent in two sets of votes. “They” ultimately decided to count the set for Hayes, and that’s why he was president.
I think the law is that, when all disputes are resolved by the “safe harbor” day, by procedures that were in place before election day (and a few other requirements), Congress is obligated to count the set of votes that the states certify. If all disputes are not resolved, Congress decides what votes to count for a state. Since not all disputes were resolved, which set of electors will count is not fixed.
Which sets of votes get counted will probably depend on the strength of the evidence that one set ought to be counted, and the strength of the public perception.
I think there are rules that determine what happens if part of Congress wishes to dispute the Vice-President’s count, but I don’t know enough about them to talk about them.