A doubler, huh. It is obvious that it is fake. Scam like this should be avoided, don't waste your time.
I think it's a way to catch up attention to people who wants easy money sending 1$ and they will send it back 2$ , I think we must not fall to this scheme inorder that we will not become a victim of scammers.
It's true, only those who wanted easy money will fall on this scam, it is a good to be true promise that we should never try, there is no such thing as easy money.