Can non-admin users sort duplicate records (without admin access)?

Yes, non-admin users can check and sort duplicate records. 
You need to enable 'Duplicate Handling' for non-admin users on the Profiles screen. Go to Settings > User Management > Profiles.

Refer to the screenshot below:



For further information on managing duplicate records, refer to the documentation below:

• Find and prevent duplicate records
• Duplicate Prevention in Modules