I'm going to assume that the double encryption password that you've mentioned is Blockchain.info's secondary password that prevents you from sending Bitcoin out of your account unless you know the secondary password.
This secondary password can be decrypted using the same brute-force techniques that you might use to recover your main password. If you're doing it by hand, you simply have to login to your Blockchain account with your Wallet ID and main password, then attempt to send Bitcoin to a new wallet. This will bring up the prompt for the secondary password.
I typically encourage people to spend a couple of hours meticulously trying to brute force their passwords by hand. This has a higher success rate than you might guess if you take the time to pull together a list of probable passwords. We have documented this process here:
https://cryptoassetrecovery.com/blog/recover-lost-blockchain-password/Take care,
Chris