Removing duplicates from EndNote is a simple process, just follow these steps after you have imported your references:
1. From the menu bar select "References" then click on "Find Duplicates" , the below box will appear
2. Any duplicates will display in this box, and you can select which record to keep or discard. After reviewing each record, select the one you wish to keep by clicking on "Keep This Record".
3. The box will reappear until all the duplicate records have been reviewed.