This is most likely due to a setting in your email account that adds a copy of emails sent via SMTP to your email sent items.
This means when you send an email via Access Recruitment CRM:
Access Recruitment CRM will send the email and create a notebook item
Your mail provider puts a copy of this in your sent items.
The sync process sees this email and syncs it into your Access Recruitment CRM database as a new notebook item
This can be resolved by:
Asking your mail provider to change your mail settings so SMTP emails are not copied into your sent items
Changing your method of sending from SMTP to Modern Authentication