A statistical impossibility. If it were a legitimate Biden bump there would have been a corresponding Trump bump.

It reminds me of that old joke of an election in New Hampshire: They were counting the votes in the small town and had 130 Democrat votes and no Republican votes when suddenly the next ballot they looked at was for a Republican. The poll workers all looked the ballot over and were puzzled so they set it aside and kept counting. And after a little while they found another Republican vote. They looked at it for awhile and looked at each other and then the head poll worker said “well, that settles it, the damn fool voted twice”. So they threw the two ballots away.