Avoiding duplicate emails


My apologies if this has been addressed in a previous post. I’m running
an installation with 3.4.1.

I have a problem with external emails going into RT becoming duplicated
when someone does a reply-all.

I have a scrip that sends to requestors and CC’s on Correspond, so if my
customer replies to a previous ticket-update the CC person gets two
emails: One from the customer (sent directly to him), and one back from
RT (via the scrip). Since both of these say essentially the same thing,
is there any way to make RT smart enough to realize “hey, looks like
this CC already got this email, no need to send it again”, or is it an
all or nothing sort of deal?