The problem occurs if you have enabled the Send e-mail notifications to the following recipients option in the advanced settings of the job and at the same time specified your e-mail address in the general e-mail notification settings (Tools > Options > E-Mail Settings).
To avoid receiving duplicate e-mail messages, disable the Send e-mail notifications to the following recipients option in the job settings (Backup Destination > Advanced > Notifications).
You can also set alternative e-mail addresses in the general Veeam Backup & Replication notification settings (Tools > Options > E-Mail Settings).
