I am told this relationship style (polygynous with multiple households) is common in Latin America, and I do know several males there who have engaged in it. These males are middle-class - doctors and the like. Polygyny also occurs in other Western cultures, although more covertly, in the form of the prestigious man and his "bit on the side" (who is usually non-reproductive, monogamous and hoping to oust the current alpha female - in the absence of contraception this would probably end up with multiple households). So I'm inclined to think it happens whenever there are massive power inequalities both between males (such that a woman is better off with a fraction of the resources of a wealthy man than with all the resources of a poor man) - and between males and females (such that wealthy men are better off "collecting" multiple poor women than marrying one wealthy one).