The basic package sun-java6-jre : 14 MB only.
http://91.189.94.219/hardy/sun-java6-jre
The big one is sun-java6-bin : 82...87 MB.
http://91.189.94.219/hardy/sun-java6-bin
Older versions of java are not removed, when you install another version.
1) They have different package names.
2) It is quite common to have two (or more?) versions installed :
Some applications / people may prefer a specific version.
There is an "easy switcher" from one version to another :
'sudo update-alternatives --config java'
You can then set the default version to any of the installed versions
like : gcc-java (gij), openjdk, sun-java5, sun-java6, sun-java7
..