As the commenters have guessed, it is probably the Debian Alternatives system in action.
If a distribution has multiple packages that contain an identically-named file, the creator of the package needs to know about it, and there needs to be a mechanism for the administrator to choose which one of them they want to use. So all the conflicting files get renamed (usually with suffixes, but this can be specified in the package metadata) and the original filename will become a symbolic link pointing to
/etc/alternatives/<original filename>. That, in turn, will be another symbolic link pointing back to one of the now-renamed files.
The system administrator can use the
update-alternatives tool to choose which version of the file will be pointed to by the original name. The other versions can still be reached using the new names.
update-alternatives tool can handle "families" of things, so when e.g. you have both the traditional and OpenBSD netcat installed and use
sudo update-alternatives --config nc to switch the default one way or another, the corresponding man page name will get switched too.
A common example would be
/usr/bin/editor. On Debian-style systems, that's a symbolic link that other programs can use to get the "default text editor on this system, whatever it is". After a minimal installation, it is likely to default to
editor example.txt will open the text file in
man editor will show the man page of
But if you install an editor that has a higher priority in the alternatives system, e.g.
joe, then it automatically becomes the new default, so now
editor example.txt will use
joe instead, and
man editor will also now show
joe's man page. You can also use
sudo update-alternatives --config editor to choose which of the installed editors you want to be the default, and once you've made a choice this way, the automatic priorities won't override it.