I read the KBA you posted here as well and have a question. Why would a person copy the Salesforce email address in the To or Cc field?
I ask because when we send an email from an incident we don't need to add a Salesforce/Remedyforce email address. Just the address(es) of the individuals we want to send the email to. This automatically results in one "Email Sent" entry in the Action History. When a person replies they are replying to the incident by default. They can copy other individuals (such as the person who sent the email) if the want. This results in just one "Email Received" entry in the Action History.
Maybe I'm missing something in your use case?
The reason that the email alert includes the support address (Added as an additional address), was to allow the system to record the email alert to the action history.
Apparently if the support address is to,from,cc an entry will be logged in the action history.
I've since removed this configuration and am reviewing alternative solutions to record the email alerts to the action history.