what does "greek meets greek" mean?

Question

I guess it's some kind of an idiom, it might either be "greek meets greek" or something like "greek meeting greek case". I need the answer desperately -don't ask why, it's so complicated :)))

Answer 1

There are several explanations. The first is a homosexual encounter. (enough said) The second deals with meeting like-minded people in a foriegn/strange country, such as two tourists from Tulsa meeting in Rome. (referring to a spontaneous alliance based upon mutual goals) The third deals with a struggle against equals (two people/nations/ideologies in conflict; inflicting terrible losses on each other, with neither having any hope of winning).
I'm sure there are others, but these are the three I'm most aware of.

p.s. Why?