I voted in the 2021 election for the current German government. Later, I moved to Berlin, where they had to repeat the election this spring due to some screw-ups back then (turns out running a marathon on election day is not a good idea). So I was asked to vote again and I did. I checked with the authorities and everything is fine.

I suppose there's some noise in any voting system, and it's fine if the magnitude is small and its distribution random. Looking at the US, I'd be more worried about gerrymandering than a few votes from the dead.