The block ciphers already make multiple passes over the data. Encrypting twice will cause you to use 2 passwords and so double the entropy in your key, but will still be vulnerable to an attack by pre-generated dictionary for known plain text. --if I understand what you mean by encrypting twice.
I was expecting this idea to be provocative and generate more response. Are there other forums you would recommend for posting this proposal?
Attachment:
signature.asc
Description: OpenPGP digital signature