The term originated in Pakistan after a man named Sibtul Shah tricked 18 commoners into investing their hard earned money into a 'scheme'. Sibtul Shah accumulated Rupees (PKR) 70 billion or (almost USD 1 billion) over a period of 18 months. He was later arrested.
A Double Shah is one who lures you to invest money in a ponzi \ pyramid scheme with an unflinching promise of unusually high return on investment.
A Double Shah takes your money on the pretext of doubling or in some cases tripling your money before handing it down to you. A Double Shah promises abnormally high returns and may produce people from your neighborhood, acquaintances, workplace to enamor you into thinking that investment in the 'scheme' is a viable option.
Shah: You should consider buying these utility bonds from me at a discounted price today and after five months there value will quadruple! You may sell it afterward.
Raj: Nay, you sound more like a double shah. I won't make the same mistake twice.