One user database for two wordpress installation

Hello,

I have checked Multisite option for wordpress, jonradio Multiple Themes and few more options and now I am totally confused.

I am running a wordpress site (http://questionpaper.org) with a paid theme, on the home page you can see the list of jobs posted for different sectors and locations.

Now what I want is, I want to use the same theme on (http://questionpaper.org/result).

I checked Multisite option but user table can’t be shared, not good for small websites, and as the theme is paid with too many features the plugins are not the solution.

Plz guide me the perfect solution.

Thanks in advance.