Technically, polygamy is having a committed relationship with more than one person simultaneously. If someone has a committed relationship, or marriage, with one person, than splits up/divorces, and has another such relationship, they're having multiple monogamies, not a polygamy. In more modern terms, I've heard of people (say, 2 men and a woman, or one man and 2 women) all having a committed relationship with each other - not only would people of the opposite sex in the relationship be committed to each other, but EVERYONE would be.. So I suppose relationships of that sort would involve either 1 straight person and 2 bisexual people or 3 bisexual people. I've also heard of the same sort of relationships (not marriages), but where the 2 men or the 2 women weren't involved with each other. Ah, complicated situations.. lol
And yes, there are [or have been] some areas where people practice polygamy, but there's 1 woman with multiple husbands.
I can't remember the name of this group, but I saw this thing on the Discovery channel or Learning channel or something on a tribal group who practiced this kind of Polygamy.. they live in tent-like structures, and there's a line hanging in front of the woman's tent. When one of her husbands is 'visiting' her and they want privacy, he hangs his cane outside on the line so the other men know not to disturb them. I thought that was kind of interesting [in a way], since any other time I'd heard of polygamy it was always one man with multiple wives.