Correct Way:

Incorrect Way (Main Mailer ID is repeated as rollover Mailer ID):

When your main Mailer ID is not in your Rollover MID's box, then you will receive the following message when your range is about to exceed 1 million. This message indicates that a rollover Mailer ID is about to be used:

When your main Mailer ID is in the Rollover MID's box, defeating the purpose of having a Rollover MID function, then you will receive the following message when your range is about to exceed 1 million, indicating the serial range is about to start repeating for the same Mailer ID:
