My interpretation is that they worked towards boosting output during the 1st quarter, which caused production to be at 1.8 million per month during the 2nd quarter, but I agree that the wording of the article is not very good.
In either case, they're stockpiling units because even after the end of the 2nd quarter (+ 20 days for shipping), Wii sales were not at that level.
My Mario Kart Wii friend code: 2707-1866-0957