Found once again a new feature from cqrlog. I should have known it is there because I have looked the source code at point what makes it, but I newer think it in that way!
I downloaded cqrlog_2.5.0_amd64.tar.gz from download page and extracted only the "cqrlog" file from cqrlog-2.5.0/usr/bin folder. I normally use my test binary 2.4.0(135) that is so close to 2.5.0 that help files etc in /usr/share/cqrlog folder do not need refreshing.
So I got the "cqrlog" file, but because i all ready have "cqrlog" file in /usr/bin (that is the 2.4.0(135)) I renamed this extracted file to "cqrlog250" and moved it to /usr/bin folder.
Now I can start the 2.4.0(135) with command "cqrlog" and the official 2.5.0 with command "cqrlog250".
First start with "cqrlog250" was surprise. It claimed that "It seems that you have not used cqrlog before...."
After some checks I found out that the binary name in /usr/bin folder, this case /usr/bin/cqrlog250 makes the user directory to be "~/.config/cqrlog250" and because that did not exist there program was right by saying that I had never used it before.
After all these years and play with source this was again totally new feature to find!
So you can have many versions of cqrlog in same computer if you just make different name binary file copies into /usr/bin. and startup icons for them (if you do not want to start them from console).
They all make their own database to ~/.config/cqrlog[your_name_extension] if you use "Save log data to local machine".
Also they all can connect to same external sql server, but in that case be aware that if your cqrlog versions are very different they may change the settings saved to sql server. And maybe logs too if the difference in cqrlog version is very big. So you have been warned about common external database server usage with multiple copies of cqrlog binary!