I have a good guess but I can't know for certain.
If I were writing the code to search I would be looking back through generations until I found either a common ancestor or the other person. In both cases the link would be 13 generations back. Either through Bohun-7 or through Huntington-28. Since it finds a match, the program stops once it sees Huntington-28. There does not seem to be any priority for match type built in.