Ah, two can play this game! There’s a lot of noise in the news feed today about Barnes & Noble’s earnings report (share price down, but down significantly less compared to last year, retail sales flat, Nook sales up). But what’s “interesting” (read: annoying, for journalists anyway) is that B&N is playing the same game Amazon plays with Kindle sales: Nook sales “doubled” over Black Friday weekend. But how many units does that represent? B&N’s not telling.