Is it possible that 2 different Log Poses have, on their route, an island in common? Or are their routes also unique?
If the routes have nothing in common, could Luffy and Roger have chosen the same route to Raftel?
I've thought in this because in the belfry of the shandora's golden bell there was a poneglyph, which had been written by Roger or by one of his crew's member.
(Bare in mind that I'm on episode 196)