In Fairy Tail there are Take Overs like Satan Soul, Beast Soul, etc. Would it be possible for more than one person to use a specific type of Take Over magic (like there would be 2 users of Satan Soul)? I wasn't sure if this magic changes depending on the individual so that all users have their own type of Take Over or if it is just learned this way.
Take Over is an advanced Caster-Type Transformation Magic. The different type of take overs shown in the Manga/Anime are Beast Soul, Animal Soul, Machina Soul, God Soul and Finally the takeover done by animals such as the Vulcan.
The description that we receive is that one can only take over the forms of "things" that you "know". In addition to these there may be other requirements for this magic. Most of the times its the defeat of the target is necessary.
In the canon ALL the Take Over Magic have been shown by unique users. The exact way to obtain any of the transformations is currently unknown. Thus it is unconfirmed if multiple users can use the same Take Over Magic.
However, from the nature of the transformations I personally classify them into the following. Thus it would be speculation to say if any of them are unique, I consider them to be of either kind. However, I consider the Lost Magics to be most unique. The answer below follows mostly my logic and speculation.
Beast Soul: Known User Elfman; Not Unique
Animal Soul: Known User Lisanna; Not Unique
Machina Soul: Known User Jenny; Not Unique
Satan Soul: Known User Mirajane; Unique
In the battle against Tartarus we learned a bit about Mirajane's abilities. It seems that she has some form of "Demon Factor" that allows her to use this powerful take over. She is immune to the Demon control techniques even opposing them. Thus it seems to be a unique transformation for her.
God Soul: Known user Dimaria (Spriggan 12); Unique
In this case we have a clear source of the unique nature of her takeover.
As the Valkyrie summons the ancient God of Time into her own body, Chronos explains to their audience that he has chosen her as his host as she is a descendant of the people of Mildian, an ancient city that worshiped him, also claiming that he and his host are a single being in this form. Source: Chapter 475
Thus the god Chronos chose Dimaria as the Vessel.
The ability to learn a takeover comes from their will also. The example I'll use is when Elfman tried to use Beast Soul the fist time and ended up killing Lisanna by accident. There are restrictions on what people can use based on their own will power and partly physical power to contain the Takeover in general. This is why Mirajane has a more powerful takeover than Elfman, she has more raw talent and a stronger will so she's not as easy to get taken over by the beast she is becoming.