I'm not sure if I understood what this option should do.
If you generate multiple playlists using different presets, and do not want tracks to be repeated among different playlists, this is already possible. You need to enable the following options in the playlist generator: http://manual.djsoft.net/radioboss/en/settings2.htm
1. Read additional file info - this is required to get the "last played" information for tracks
2. Use the Last Played tag - use last played information to prevent track repeats
3. Repeat protection: Take into accounts tracks in the playlist window - prevent repeats for tracks that are not played yet, but present in the playlist window and will be played soon.