Next to checking for duplicate records when saving, Duplicate Check can also scan for duplicates while you are creating or editing a record, so even before you hit the Save button.
The settings for preventing duplicates can be set independently for creating or updating a record.

Prerequisites

• You have the Duplicate Check User role
• Searching for duplicates while creating or editing a record should be enabled in the Feature Activation & Setup settings of the entity you are saving. Make sure one or both of the
  As-you-type duplicate notification while updating an existing <Entity> and
  As-you-type duplicate notification while creating a new <Entity> settings
  are configured and activated. Read more in Duplicate Prevention‍.

Checking for duplicates while creating or editing

In the settings you have indicated which fields should be filled or updated before the duplicate check starts. When the required fields are populated or changed, as soon as you click outside the last required field, Duplicate Check starts scanning existing records for potential duplicates. The fields you set in the scenario(s)‍ are compared, and if they match close enough a warning is shown.

• At the top you see a warning stating you are about to create a duplicate record. The message text can be changed in the settings‍.
  
• The Duplicates Found tab header shows a counter to indicate that one or more duplicates were found, but the focus stays on the Summary tab.
• You can continue creating or editing the card, and save it. If you also have enabled duplicate check upon saving (with or without blocking), that check will start when you click Save.
• To review the duplicates, go to tab Duplicates Found.
• The Duplicates Found overview shows the duplicate score of the existing records. This score is calculated based on the Fields To Compare and other settings in the scenario.
• The overview also shows some fields of the existing records, so you can quickly determine whether it indeed concerns a duplicate. These fields are set in the Result Fields‍ setting.
• If you want to view or edit an existing record, click Open Record  at right to open it in a new tab.