Let's wargame this. If I was a computer vote fraudster I'd have it take some percent of random votes and print a code pattern in the Biden oval. It could even be barely perceptible to people. If it was actually Biden it just gets a little extra ink.

You fill in Trump, machine prints a code on Biden and gives him the vote. Recount time, run through the machine it scans Trump and Biden and instead of rejecting it for overvote it counts it as Biden because it sees the pattern.

The machine could do this even if the printer is before the scanner and the recount gives the same totals.

Only a manual recount would detect this.