Why in a single KDE environment some applications (e.g. Krusader) show Platform Version 4.14.10 and some, like Konsole, report Frameworks Version 5.11.0 ?

Does this mean that there are 2 platform branches installed in my ArchLinux instalation?

I noticed these packages:

local/kdebase-lib 15.04.3-1
KDE libraries for the basic desktop applications

local/kdelibs 4.14.10-1
KDE Core Libraries

local/kdelibs4support 5.11.0-1 (kf5-aids)
Porting aid from KDELibs4

Do I have installed concurrently KDE 4 and 5 or just one of them and the porting for another?

rsupremo wrote:Why in a single KDE environment some applications (e.g. Krusader) show Platform Version 4.14.10 and some, like Konsole, report Frameworks Version 5.11.0 ?

Because some your applications are using KDE (Libraries) 4, while others are KDE Frameworks5 based.

Does this mean that there are 2 platform branches installed in my ArchLinux instalation?

Yes.
kdelibs4 for "KDE4" based applications, and KDE Frameworks5 for KF5 based ones.

And you could even have KDE3 too, on openSUSE at least...

Do I have installed concurrently KDE 4 and 5 or just one of them and the porting for another?

No.
There is no "KDE 4" or "KDE 5".

You have some applications that are based on kdelibs4, and some that use the newer Frameworks5.

The kdelibs4support that you mention is for helping to port KDE4 applications to KF5, but that's by far not all of KDE Frameworks5...
And KDE4 applications don't magically use KF5 either when it is installed, they still use KDE4 libraries only, they have to be ported to KF5 by their developers.