I have the same problem. Here the details of the environment:
Windows 7 Professional 64-bit
Outlook 2013 using a mail account from outlook.com via Active Sync
Create a sub folder (e.g. "Projects") below "Gesendete Elemente" (German for "Sent Items")
Move an E-Mail from "Gesendete Elemente" to "Projects"
-> ESET Outlook plugin will duplicate all recipients and all attachments
Problem could be reproduced for:
- Smart Security 7.0.302.26
- Smart Security 8.0.304.4