One number generally corresponds to the official publisher, and the other to whatever other publisher is cited. You can generally just check the page numbers against the "cite as" citation given at the top of the document to see which number corresponds to which. ie something reads "cite as 117 Wash.App. 483, 120 P.3d 172", the numbers given on the first page will look like *483**172, and the second page *484**173. First number given corresponds to the first publisher, and the second to the second.