Avast Security-Outlook 2011 messages show up twice in Sent Items

Messages have just started today showing up twice in my sent items folder. Once with the Avast scan header, one without the Avast header.

Searches say to disable the Avast signature for incoming and outgoing emails, but Avast Security 13.4 doesn’t have that option. There is no General tab.

Anyone else having this issue? Thank you.

Would you mind to share a screenshot?
Mail shield options are in “Preferences > Shields > Mail Shield”.