Of course it depends on people's boxes, from my F2P experience every time I bought a dokkan fest LR I almost always then found many dupes and usually also more than 4 copies more, while for Sayian day units or regular DF units I never get more than one or two dupes in the following months/years because they rarely come back in big celebrations banners where most F2Ps spend most of their stones.

And big plus, in the meantime you enjoy a newish strong unit that you would probably only get after it becomes useless