Writing in the context of the discovery process in civil litigation, Anne Kershaw and Joseph Howie write in Law Technology News of the fallacy of reviewing identical copies

of electronic messages as if each were, in effect, a separate paper document.

In civil litigation, this increases delay and cost.

In the context of intelligence analysis – particularly open-source – it’s a point ignored at the risk of missing important data – or reviewing it too late. A single item duplicated in volume is still a single item – the first is signal, the others merely noise.