apt-get trying to install same package version again

[Wolfgang Pfeiffer <roto@gmx.net>]

Hi All

The installed version number of gtkpbbuttons is the latest one: I didn't
get and install it via my apt-sources list, but, if I see correctly,
from Matthias Grimm, the authors site.

  apt-cache policy gtkpbbuttons
gtkpbbuttons:
  Installed: 0.6.3-1
  Candidate: 0.6.3-1
  Version Table:
     0.6.3-1 0
        990 http://ftp.cz.debian.org unstable/main Packages
 *** 0.6.3-1 0
        100 /var/lib/dpkg/status

But with a dist-upgrade or a simple
apt-get/aptitude install gtkpbbuttons
both apt-get and aptitude want to upgrade to the same gtkpbbuttons
version.

I suspect, that the package system does not look at the package version
to decide whether a package has to be updated but to *some sort* of time
stamps on the installed packages. And if the time stamp on some
installed package is older than the one installable from debian
repositories then the installed one gets overwritten by the package
system, no matter whether the same version number is getting installed
again or not. 
Positive?

If yes: How can I force apt-get/aptitude to behave, and *not* install
the same version a second time?

Or is "holding" a package the only option to prevent it from being
overwritten with a package of the same version number?

Please tell me someone I missed something.

Thanks in anticipation.

Best Regards
Wolfgang
-- 
Profile, links: http://profiles.yahoo.com/wolfgangpfeiffer