Salesforce Email to Case creating duplicate records

1. Send an email to Service Email Address(Long Email Address from Salesforce). Check whether it creates duplicate cases.

2. Request an Inbound Email Snapshot – https://help.salesforce.com/s/articleView?id=sf.inbound_email_snapshot_request.htm&type=5. Check whether the customer facing email address is sending two emails to Salesforce Service Email Address.

3. Set up debug logs and check whether any of the automation(Flow, Process Builder, Trigger, etc) are creating duplicate records due to recursion.

Email-to-Case may create duplicate Cases Help Article – https://help.salesforce.com/s/articleView?id=000315574&type=1