SA-exim issue or SA issue?

Hi,

	I've got MX1 and MX2, both running SA-Exim 4.2/Exim 4.6.6/SA 3.1.8.   
MX1 is where all the mail ends up and where mail is POP'd/IMAP'd,  
etc.  MX2 is simply a backup MX.  I've got a couple of issues, but  
I'm not 100% sure if they are SA-Exim issues or SA issues, so forgive  
me if I'm off topic.

First, I'm seeing an issue where mail tagged as spam by SA-Exim on  
MX2 is tagged again by MX1.  This leads to the rewrite_header being  
applied twice; once on MX2 and again on MX1.  I assume this is a SA  
issue, but I figure I'd see if anyone here can confirm that, or  
suggest it may be something obscure with SA-Exim.

Secondly, I think this is more about clarification for me:  I see  
some cases where the X-First-Run-Spamscore and the score in the X- 
Spam-Status are different.  I haven't been able to find a pattern yet  
on when exactly that happens, but I'm wondering if anyone has seen  
this behavior before if they can give me an idea about where to look.

Thanks in advance.