kdepim related applications such as kmail2, kontact, korganizer missing many version in the bug tracker. Furthermore, they are sometimes overlapping.
example: kmail2
I don't know what you mean with 'overlapping'.
What are all the missing versions? The kmail git repository doesn't have any tags, so I can't get the version numbers from there.
I found the same request (missing versions) in the regular bug-tracker which lists the versions in more detail: https://bugs.kde.org/show_bug.cgi?id=335654#c7
Regarding the overlapping: I thought 5.1 is a container for the whole 5.1.x releases, but it seems that 5.1.0 was named 5.1.
I've mailed the release team and PIM developers regarding this to figure out what the proper solution here is going forward.
Once that's been clarified we can sort out the versions on Bugzilla.