Rhodactis mushrooms in general are pretty common. I’m not sure about the specific color morph you have. They don’t typically spread like crazy, that’s more discomas, but in the right tank environment they will definitely reproduce. Mushrooms are usually pretty easy to sell or give away as well. Try to isolate them to a rock if you want to try to make extra sure they don’t go where you don’t want them to. But, mushrooms can detach and move, so you might not be 100% successful.