I think this time is Nielsen's fault about the numbers. Not only Billboard, 'cause RoughStock (a completely accurate Country music site) reported Carrie with the same number. But looking at Kworb numbers, they are the same numbers but 65k instead of 56k
I seriously think Carrie sold more than 56k, 56k seems too low for me and even Kworb estimated "Stitches" with 66k sold, and selling actually 10k less doesn't seem right to me
(And I know what you're gonna say, but I prefer believe in Kworb)