If this is a major problem, I would imagine site 'B' (the true originator) could actually embargo their new content until after Googlebot visits it, then open it to the public.<p>Combined with a few tricks to send Google to the newest content – fresh sitemaps, PubSubHubBub, links from any other pages Googlebot is currently visiting on the site – this probably wouldn't delay the release of the content to the human audience by very much.