NZBDonkey does only add NZB files to your usenet client upon an user interaction (i.e by clicking on a NZBlnk link, choosing "Get NZB file" from the context menu, or when manually downloading an NZB file with option "intercept NZB downloads" enabled) and only one NZB file per user interaction. It is true that you might get "wrong" NZB files if the header/subject was not unique enough and the NZB search engines did not return the correct NZB file as the first hit in the search results, but if you had 10000 unwanted NZBs file sent to your usenet client you probably used NZBDonkey the wrong way. If you really think this is a problem with NZBDonkey then, please open a "issue" on the NZBDonkey github page (https://github.com/Tensai75/NZBDonkey).