Remove many duplicate entries from Zotero

1. Open up the Duplicate Items folder.
2. Go to Tools > Developer > Run JavaScript
3. Run the snippet:

   var DupPane = Zotero.getZoteroPanes();
    for(var i = 0; i < 100; i++) {
    await new Promise(r => setTimeout(r, 1000));
    DupPane[0].mergeSelectedItems();
    Zotero_Duplicates_Pane.merge();
    }

Basically, this clicks the "Merge X items" button 100 times with a second waiting time in between.

Source: https://forums.zotero.org/discussion/comment/347581/#Comment_347581