Bitcoin doublers are scams. No doublers are legit and paying. Evidence? Here
https://bitcointalk.org/index.php?topic=1197091.0. Just avoid them. They offer crazy figures and make you wonder how can they do that in a short period of time? That is very suspicious. If doublers are true, i should be a millionaire by now. I have checked the site and i saw small amounts that has been deposited and doubled. They make all the amounts small to make it believable. Also the comment above me is right. It's a cheap domain(actually it's for free). Means the site is disposable site.