What is the purpose of apache2 having PKGNAME of "apache" (without 2)?

For multiple versions that can't be installed at once, I think it makes
sense to use the basic packagename.  The alternative is to manage a
whole bunch of CONFLICTS, and that seems messy.

I think that what you are asking for is a rule that only one PKGPATH
entry create a package with a given PKGNAME.  (In general, I find that
the package name isn't really unique, and that when doing upgrades one
has to look up the PKGPATH and check that.)

Once we have a rule like that, we have to either put the version on
every package, or decide which package gets the unadorned version.  Then
this gets to change.  All in all, it seems to create more ugliness than
it solves.

What about emacs?  How many examples of the problem are there now?

How hard is it to use PKGPATH (for updating) or version choices (or new
installs)?

I don't have a good answer for the download problem.

My real objection would be to gratuitously changing the PKGPATH.  That
messes up pkg_rolling-replace.  But that's orthogonal to your issue.