I'm in testing stage with Support Professional plan.
When I replyed to a ticket from the agent's ticket interface, this created a duplicate ticket with "Re: original_title" as title and considered as a proactive ticket on behalf of the requester.
Can it be because I created a fictive "requester" using my gmail account and tied it to an organization for which the email domain was defined and not gmail.com ?
Anyway, I changed the requester's organization, tested another reply now and this time, it didn't create a duplicate ticket. So if this was the reason, no problem, but I just wanted to be sure why and how this can happen.