Find pairs of country centroids relatively further away from other country centroids. They are sorted by the ratio of the distance between the closest other centroid and the distance between them. As a hint you are shown this ratio and the closest other centroid(s) to them.
Data from Portland State University (https://www.pdx.edu/econ/country-geography-data), for missing countries from CIA (https://www.cia.gov/library/publications/the-world-factbook/fields/2011.html)
If the closest other centroid isn't the same for the two twins, you are shown both