By default, Shoviv Migration tool migrates complete data of source mailbox to target exchange mailbox at once and if you try to migrate the same source mailbox again, it creates duplicate items in the target.
In case you have made some changes in source mailboxes or want to migrate those items which appear after performing the migration process if you will use the regular migration method; it will create duplicate items in the target mailbox. To prevent this problem you can use the option provided by the Shoviv software to prevent duplicate items being migrated in the target mailbox.
Please use below steps to migrate and mailbox without creating duplicate items in target mailbox:
When you perform the migration for and source mailbox for the first time, please check “Export Duplicate Items (Alternatively uncheck to filter already processed Items)" option. It will migrate all the items for the first time (In case you are wondering why to check this option when it’s clearly mentioned that it will create duplicate item, it's because there is no chance to appear duplicate item in first migration, by checking this option, migration speed will be increased as the software will not perform to check for duplicate item.)
Now all Items from source mailboxes to target are migrated.
Now if you want to perform the migration process for the second time to include those items which appear after starting the first or previous migration process.Firstly make sure that if you had performed any folder mapping in the primary migration, please configure the same folder mapping this well.
In case you are performing the mapping differently, it will not be able to prevent from creating duplicate items in a different folder of the target mailbox.
Please check the option "Export Duplicate Items (Alternatively uncheck to filter already processed Items)" and it will prevent migrating those items which were migrated previously.
Though this option is very efficient and effective, it still takes time to perform the migration as it performs check for the individual email items whether it's already present in the target folder of the mailbox or not. An alternative option is to perform migration is by applying the date filter option, i.e. if your last migration was started on 20-Jan-2018 and you want to perform the migration for those items which appears after 20-Jan-2018, you can select date filter and choose the date 21-Jan-2018 for "from" field. And for "To" field you can choose your current date.
Date filter option is relatively faster than the other option and is often recommended if you want to perform migration promptly.