There is no such thing.
No its a scam. The only way to double your money is by working for it.
This is against Runescape code of conduct. If you need in game money you can use real life money to buy a bond on the Runescape website, then sell that in game.
LOts of quests offer money. Doing achievement diary also gives you money.
If you use one you will automatically get banned
There are no safe sites to get RuneScape money, or power-levelling. Since it is against the rules, if you are caught, you risk your account, it's as simple as that.
go to the halmet and click on the money bag
There are no money cheats in RuneScape.
Buying Runescape accounts really isn't recommended. It is against the game's terms of service, and accounts will be returned to the origional owner upon request. All the levels you've trained and wealth you put onto the account can be easily lost.
Earn RuneScape money yourself and stop relying on money generators.
You can't get infinite gold on runescape.
There are various Runescape money making methods, however there is no hacks/cheats you can download to duplicate money or items.
It is safe is you buy it from other players, for RuneScape coins. If you buy with real money from some website, you are breaking the RuneScape rules, and it is therefore not safe.