I would be interested in those calculations about how big the universe would have to be to have repeating Earths if anyone recalls where they saw them.

http://lesswrong.com/lw/ws/for_the_people_who_are_still_alive/

If the universe is spatially infinite, then, on average, we should expect that no more than 10^10^29 meters away is an exact duplicate of you. If you're looking for an exact duplicate of a Hubble volume - an object the size of our observable universe - then you should still on average only need to look 10^10^115 lightyears. (These are numbers based on a highly conservative counting of "physically possible" states, e.g. packing the whole Hubble volume with potential protons at maximum density given by the Pauli Exclusion principle, and then allowing each proton to be present or absent.)

Google search query: "duplicate earth lightyears away site:lesswrong.com". Estimated time to search and go through first page: 30 seconds.