Maybe both sites have the same owner.
Cryptoniuus' FAQ is a copy-paste of cryptodouble's, including the part about cryptodouble not accepting fiat... whilst Cryptonus only accepts fiat :/
Fail at pasting.
Some people are lazy even admins cant get it wright leaves it wide open to easily detect could well be a scam who knows but 99.9% of copy cat sites lead to 100000% scam and never pay.