The system is able to identify two or more references as duplicates. Duplicates have quite common occurrence even within a single set of results from one source of references. Another moment when you benefit from deduplication is when you run a search on the same topic in multiple different databases, but in your final result list, you naturally want to have each reference only once.

Duplicates removal is the reason why the numbers of references in resources and in Preview can differ.

1. Duplicates which are identified by ID (meaning they are from the same database) are removed automatically, so only one reference is displayed in Preview.
2. Other duplicates are identified by a combination of different criteria. You can set these criteria in the project settings:

ID (it cannot be disabled)

In case of identical ID, only one reference is displayed in Preview.

DOI

Identifying duplicates based on article's DOI.

URL

Identifying duplicates based on article's URL.

Source/Vol/Year/Page

Identifying duplicates based on journal's name, volume, publication year and start page of the article.

Title/Page

Identifying duplicates based on title and start page of the article.

Title/Authors/Year/Page

Identifying duplicates based on title, authors, publication year and and start page of the article.

When the active rules applies to two or more articles (e.g. has the same title and start page), then articles are evaluated as duplicates. Only the first one is displayed in the result list and the others are assigned to it. Such records are marked with an icon with number of duplicates. If, however, the user discovers that there are no duplicates, he can turn the duplicate into a standard record by clicking the Not duplicate button.

If the duplicate also contains an abstract or DOI, it will be automatically used to complete the record.

<aside> 💡 For a quick overview of duplicates, use the Other filter in the left menu, where records with duplicates (from point 2) are listed.

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