Its done all the time. And generally safe if thawed properly. But each time a meat is froze and thawed, it opens it up to air, and bacteria. Meat will start spoiling as soon as blood stops pumping thru it.
If you thaw meat by leaving at room temps, then refreeze, this where one can get sick or the meat starts smelling funny.
if you ever go out in the bush in Canada and kill a moose, you have to get the meat home. The standard practice is to quick freeze the meat in extreme freeze, and the meat thaws on the way home to some extent. Then you refreeze it at home.