at the time when yobit.net exchange newly launched i had managed to get 3 vouchers and those 3vouchers give me 1ltc each. that time i bought a lot of doge with them and forget it for 1year. after that when i again visited yobit for some price watching porpuse i logged in and boom i found so many doge coins waiting for me there. they are not doubled but they are atleast 40% increased.