tedster - 3:42 am on Sep 8, 2012 (gmt 0)

maybe they are just trying to find out which pages on a site are the best for the query when there are multiple possible pages by a/b testing

Given the preference Google has for machine learning, I'd say that your idea here has a high chance of being accurate. Now the question I'd ask is why the choice they are being given seems so unclear to them - or how can an affected site clarify the ideal page.

Are others who are seeing zombie traffic also seeing this pattern - when conversions go down the landing page Google is ranking is different?