The story you cite is a paperwork issue. The woman wasn't actually living with two men at the same time, but may have been committing immigration fraud (I can't find the case in the BC Judgments data base, so it's not clear if she was convicted). It's fairly common for people to remarry before their previous divorce becomes final. This is technically bigamy (which is polygamy, just the least form of it) but is most unlikely to be prosecuted absent some aggravating circumstance like immigration involvement.  The situation where a man is actually carrying on two marriages at the same time is quite different. I've never heard of a woman doing that.