You do get the idea. Assuming that before taking your existence into account you put .5 probability on each type of planet, then the two options you give are the standard SIA and SSA answers respectively. The former involves treating your existence as more evidence than just that someone exists, as I was suggesting in this post.

I think everyone agrees that in the multiverse case (or any case where everyone exists in the same world) you should reason as you do above. The question is whether to treat cases where the people are in different possible worlds analogously with those where the people are just on different planets or in different rooms for instance.