I open a few mini play lists in Excel so I have a good evidence of the content of all mini play lists-name and location of each song. Having lenght of each song too would be perfect
So you really need the duration only for reporting purposes. In this case you could either write a special log file for mini-playlists, similar to the LogMPL add-in (see http://www.wolosoft.com/en/raduga/add-ins.html)
Or you can convert the mini-playlist file to a report file containing additional information about each item. I can help you to create such a converter, but only if you have a valid Raduga license.