This is part of Strong Encryption Specification (SES) format. Even though we could easily add support for it, we are not allowed to do this because SES is a patented technology and PKWARE refused to grant us a license:
"Regarding your request for a license for the Single Password Symmetric Encryption technology, PKWARE is discontinuing this licensing program and no further licenses will be issued under it. We are unable to grant your request." - PKWARE, Inc.
Sadly, this means we can't add support for ZIP content list encryption. Sorry!
Double-zipping approach you used is the recommended workaround for this, and it's sufficient to only encrypt the second ZIP.