Carstensz or Kosciuszko: which one counts as the seventh summit, and do I need both?
What about Kosciuszko? Dick Bass climbed it.
The 7 summits have two versions because the highest point of Australia and Oceania depends on where the continent ends. Dick Bass, who invented the challenge and completed it in 1985, used Kosciuszko, 2,228 m, the highest point of the Australian mainland; Reinhold Messner's version uses Carstensz Pyramid.
The full answer, kept up to date: What about Kosciuszko? Dick Bass climbed it.