[exim] Subject rewriting

Hi,

I need to change the subject when the message is considered as spam,
*and* when there is an SPF problem.

I use the following method:

1 - for SPF:
     # remove old subject
     remove_header=Subject
     # create a new subject
     add_header = Subject: *** SPF Error *** $rh_Subject:

2 - for SPAM:
     # remove old subject
     remove_header=Subject
     # create a new subject
     add_header = Subject: ***SPAM (score: $spam_score)*** $rh_Subject:

It works fine when either of these two cases occur.
But when both occur at the same time, I don't get the expected result.
In this case, I get two "Subject" headers.

Is there a way to have a subject like:
Subject: ***SPAM (score: $spam_score)*** *** SPF Error *** xxxxxxxxxx
xxxxxxx being the original subject

Furthermore, would it be better to use $h_header?

Thanks in advance for any idea.