Positioned folder contents get duplicated in the opened file list when you click 'Browse file list' in a certain search result more than once

To reproduce:
- search for a common term
- click Browse file list on a search result
- file list window opens
- go back to search and click Browse file list again on the same search result

Expected :
The file list tab gets dirty or the window gets focused (depending on the 'Open new filelist windows in the background' setting), position and content doesn't changed.

Actual:
The file list tab gets dirty or the window gets focused (depending on the 'Open new filelist windows in the background' setting), position remains but the folder content will get doubled (and any subsequent Browse click adds the same content again and again).