Can Notes Migrator for Exchange set the forwarding in Exchange for mail to be deliverer to both Exchange and Notes?
This is not possible with Notes Migrator for Exchange.
If mail is routed to both Exchange and Notes duplicates could occur when Migrating the Notes mailbox as the Messages IDs could be different.
Notes Migrator for Exchange uses the Notes Message ID to see if the message needs to be migrated, if the message ID is not seen in Exchange it will migrate the message.