[GeorgeCostanza]

1. Add YouTube video to linkgrabber via clipboard monitoring

2. Download

3. Restart JD

4. Try to add same YouTube video to linkgrabber via clipboad monitoring again

Result:
JDownloader will add it to the linkgrabber, but not mark it as already downloaded

i've disabled the dupe manager, restarted JD, then re-enabled the dupe manager and restarted JD multiple times