Yes we did, and since it came up again, I don't think it is real. The person posting knows more about the aquarium than they are letting on. If my wife sold mine it wouldn't say ballast on the post and she wouldn't know what size it was.
I think I read somewhere that if you get 2 mandarins you have to introduce them at the same time and they have to be m/f. I dont think you can add one if one is already established in the tank. At least thats what the interwebz told me so it must be true!