If you install different modules and even older ones it might happen that older jar versions are installed.
I want only the latest version of the jar in my userlib folder or Mendix Runtime is loading only the latest one (like OSGi framework)
For Siemens employees a standalone c# based util can be downloaded from https://code.siemens.com/schoelch.matthias/mendix-duplicate-jar-remover
Sorry I have developed this during my working time. So I have to ask my manager. Its not as complicated so if I got the OK I will push it to github.
Yes, please. Maintenance of the jar-files is definitely a task suitable for the IDE.
Btw. what a pitty that Siemens is not publishing their nice tool to the Mendix community.