Chapter 4 FortiOS Carrier : Carrier web-based manager settings : Duplicate Message
  
Duplicate Message
Duplicate message protection for MM1 messages prevents multiple subscribers from sending duplicate messages to your MMSC. Duplicate message protection for MM4 messages prevents another service provider from sending duplicate messages from the same subscriber to your MMSC.
The unit keeps track of the sent messages. If the same message appears more often than the threshold value that you have configured, action is taken. Possible actions are logging the duplicate messages, blocking or intercepting them, archiving, and sending an alert to inform an administrator that duplicate messages are occurring.