Duplicate records can be found in several ways using Duplicate Check. One way is by checking for duplicates when you are opening an existing record, also known as 'DC Live'. 

Prerequisites

• You have the Duplicate Check User or Duplicate Check Admin role
• Searching for duplicates upon opening a record should be enabled in the Feature Activation & Setup settings of the entity you are saving. Make sure the Duplicate search when opening a <Entity> setting is configured and activated. Read more in Duplicate Prevention‍.

Checking for duplicates upon opening

When you open an existing record, Duplicate Check will scan the entity's other records to see if there are any records that match the record you just opened. The fields you set in the scenario(s)‍ are compared, and if they match close enough a warning is shown.

If a duplicate record is found, the Duplicates Found tab is added. Furthermore, at the top of the record you see a warning stating a duplicate record was found for your record. The warning text can be changed in the settings‍.

Go to the Duplicates Found tab to review the duplicate records.

• The 'Duplicates Found' overview shows the duplicate score of the found records. This score is calculated based on the Fields To Compare and other settings in the scenario.
• The overview also shows some fields of each duplicate record, so you can quickly determine whether it indeed concerns a duplicate. Which fields are shown can be changed in the Result Fields‍ setting.

Processing duplicates

• To review a found record in detail to see if it really concerns a duplicate of your initial record, click Open Record  at the right. If the record is not a duplicate after all, edit it so that it doesn't show up as a duplicate anymore, if needed.
• If the records are indeed duplicates, you can Merge them with the initial record.
  • At the right of a duplicate record, click Merge . Or,
  • Select the duplicate records you want to merge, and click Merge Selected Records  at top left.When selecting multiple records, note that they will be merged not only with each other, but also with the initial record.

Read more about merging records here‍.