innobackupex --apply-log source and destination folder?

I’m not sure what exactly you mean. Let suppose you took backup on /backup/backup1/ directory and you want to prepare backup (–apply-log) on different folder by keeping backup intact before prepare on /backup/backup1/ directory.
You can make a copy of /backup/backup1/ to /backup/backup2/ directory for instance and use --apply-log on destination folder /backup/backup2/ directory.