As you import and add references to your library, you will probably end up with several duplicate references in your library. This often happens when you import sets of results from two different databases or from two searches on the same database.
Duplicates can cause problems when working with Word, as you can inadvertently end up using different versions of the same citation, which generates multiple entries in your bibliography where there should only be one entry.
EndNote can help to remove duplicates but you should also perform your own deduplication to keep your library clean and usable.
How to find duplicate references in EndNote
Watch our video on how to find duplicate references in EndNote:
To identify duplicate items:
- Click on “Library” on the top toolbar, then click “Find Duplicates”.
- A new window will show you the duplicates that have been found and invite you to select which one to keep. It shows you the details of two matching items, with any differences highlighted in blue. One of the duplicates might contain more detail than the other, so you might choose to keep that one.
- To select the item to keep, click “Keep This Record”. The other reference will be moved to the Trash. If you want to keep both, click “Skip”.
Use different duplication criteria
EndNote searches for duplicates in your library using its default criteria: references of the same type with matching author, year and title fields.
For a thorough duplication check, we recommend you use these additional criteria:
- Year, Author, Pages
- Year, Journal, Title
- Author, Journal, Title
- Year, Title.
To run your own duplication criteria:
- Go to “Edit”, click “Preferences” and then “Duplicates”.
- Select or unselect fields to change the criteria, then click “OK”.
- Click “Library” and “Find Duplicates” again to find duplicate references that match your new criteria.
Choose the references you want to keep and those you want to delete, and repeat until you have used all the different combinations of criteria suggested above.
Manually check for duplicates
The EndNote “Find Duplicates” tool might not identify every duplicate record due to differences in the punctuation and spelling of journal names, article titles, and author information. To catch them all, you should also do a final manual check for duplicates.
Sort the references in your library by clicking on the “Author” or “Title” column headings. You can then scan down the list in order to spot any remaining duplicates.
Delete a duplicate reference by right-clicking on it and selecting “Move References to Trash”. You can also press “Ctrl+D” on your computer keyboard.
Large reference sets and systematic reviews
For large numbers of references in a systematic review, you could speed up the deduplication process by using software such as the SR-Accelerator Deduplicator, produced by Bond Unviersity in Australia. This software is compatible with EndNote libraries.