Usually you'd either track known errors in the dataset (implying that the companies had either bought it from PDL or copied the leak), or you'd ask the banks (w

Usually you'd either track known errors in the dataset (implying that the companies had either bought it from PDL or copied the leak), or you'd ask the banks (who do have a presence) which accounts were paying them and who owned the accounts. If Bitcoin's involved at all, you assume there's something fishy going on and investigate accordingly. (Assuming anyone were bothered enough to actually do this, of course.)