To answer the original question:
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I am just curious to hear peoples thoughts on the matter. Some might see that as Polygamy and some may not. Is there any area where that's legal to marry more than 1 person?
It is polygamy, as polygamy is a well defined term. I am sure there are places or times where it is/was legal. However, in most countries as you file legal documents, you will in legal documents, such as those concerning taxes, you would only list one spouse. There is no law preventing you from referring to multiple people as your husbands or wives, except when it comes to legal documents.
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Do you think that if your bisexual you can instead marry one person and have another as a housemate of sorts? So where does it end though, do you get 50 husbands and wives? I just am wondering , because I don't see many people talking about bisexual marriages.
I have several friends that are polyamorous and they can handle that well enough and so can their partners. I, however, could not. I identify as pansexual (a superset of sexualities of which bisexuality is a subset) and my spouse is also pansexual. Neither of us could manage a polyamorous relationship and we don't want to

For those that can and want to, that is their choice and is quite possible as I have seen by my friends' examples.
The issue that I have seen, however, is that polyamorous individuals do not tend keep multiple partners for an extended period of time (for example, forever) and they don't desire marriage. The friends that I was referring to really do love their partners, they just don't want to make it a marriage.
I am pretty sure that a polygamous marriage
could work just as easily as a monogamous marriage, but I don't know how much that says. Many people are pessimists when it comes to the divorce rate. If 50% of marriages end in divorce, 50% last forever.