Permit to upload a new package with the same name-version of another package already uploaded (PPA)

The problem in doing that for packages that were already published is that client of your PPA will be confused. Also there is a high possibility that the new source will result in binaries that cannot be published because of copies of the old version may still published in the archive.

Try to imagine a archive as a VCS, you won't ask to replace a revision, would you ?

What's the real problem in increasing the package version ?

If I work on a package for Ubuntu and I upload it to my PPA to testbuild it and after I need to add a patch or similar I need to update the revision number. If I forgot to increase it PPA reject the package, or if the package is copied to Ubuntu (for example https://edge.launchpad.net/ubuntu/intrepid/+source/koffice2/1:1.9.96.0~that.is.really.1.9.95.9-1ubuntu1.3 ) it will have the wrong number version.
Also isn't ideal for a developer to change each time the revision number, don't you think?

bug #263301 re-raised this discussion with new details. Let's address the duplication.

I think the current functionality is a feature (as Emmett discusses) and not a bug. My advice to the reporter is to be really careful if you have to roll your own tarball. Using a get-orig-source rule to automate this process will reduce the risk of error.

The problem is not the tarball, but the possibility to update a new version <= the updated version using -f flag (as REVU for example does).

REVU is unique (for good reason) in accepting new tarballs of the same
versions. The -f flag just ignores the .upload file. If you rm that it
has the same effect. It has no effect on the distant end.