Currently, when we change the event template, all the communication
lines linked with are added to the event. That means, even if some of
the lines are sent, and if the new templates lines that has exact same
configuration than the sent ones, they are still added to the event,
which means the same mails will be sent again to the attendees.
With this commit, we check that the communication line being added
(as a result of template change) has the same configuration against
any of the already sent one, it is skipped. As a result, attendees
will not be spammed with the same emails.
taskID-2811310
closesodoo/odoo#89961
Signed-off-by: Thibault Delavallee (tde) <tde@openerp.com>