XYplorer Beta Club

In the menu "Tools" is the entry "Customize File Associations..." and also "List Management > Portable File Associations...".

For me it looks like both entries are doing exactly the same, is there any reason why we have both of these menu-entries?

Yes, usability / user-friendliness. I think it deserves a prominent place, at the same time it belongs to List Management. I know that some folks get the creeps with this kind of redundancy, but I have no problems with it when it's good.