You can control this with the HISTCONTROL and HISTIGNORE environment variables: http://askubuntu.com/questions/15926/how-to-avoid-duplicate-...

Much to my dismay this is not true. By default debian is configured to `ignoreboth` ie dupes and spaces. Like you I also change the debian default for HISTCONTROL. Lines 11-13 of /etc/skel/.bashrc:[^1]

  # don't put duplicate lines or lines starting with space in the history.
  # See bash(1) for more options
  HISTCONTROL=ignoreboth

[^1]: https://bazaar.launchpad.net/~doko/+junk/pkg-bash-debian/vie...

Provenance for /etc/skel/.bashrc:

  dfc@ronin:~$ dlocate /etc/skel/
  bash: /etc/skel/.bash_logout
  bash: /etc/skel/.bashrc
  bash: /etc/skel/.profile
  dfc@ronin:~$ apt-cache showsrc bash |grep ^Vcs-
  Vcs-Browser: https://code.launchpad.net/~doko/+junk/pkg-bash-debian
  Vcs-Bzr: http://bazaar.launchpad.net/~doko/+junk/pkg-bash-debian

It's controlled by the HISTCONTROL variable in bash. If it contains 'ignorespace' (or 'ignoreboth' to ignore duplicates as well). Check the man page for more details.