I believe having a single wiki would be a better option, as having two would just confuse things.
Having a second wiki to boost search ratings isn't, imo, a valid reason to keep it running, and the level of 'control' users have over the official wiki is more than sufficient.
Having a 3rd party wiki was a great idea when there wasn't an alternative, but now that there is, my vote would be to stop using the 3rd party wiki, and perhaps replacing it with something along the lines of 'the official plutohome wiki can now be found here' sort of thing.
...now I just need sometime to fix my very broken installation so I can contribute to the wiki
Cheers,
-Kent