In the social sciences, is it easier to get a post doc than a PhD?
If you already have a PhD, the chances of being admitted into a second PhD program are quite low, I would imagine. Furthermore, I would not recommend such a strategy: the possibility of being labeled as a "perpetual student" could have negative ramifications on one's career.

That said, there is funding for post-doctoral associates in addition to graduate students, even in the social sciences; in particular, there are a number of fellowships that are designed specifically for postdoctoral candidates in the humanities and social sciences. Of course, there is relatively more funding for PhD's than for postdoctoral associates.