Can I make mutt see two destination addresses as just one?

[Chris Green]

I belong to a mailing list where *sometimes* messages appear to come
from two similar addresses, the headers have a To: line as follows:-

    To: ixion at ixiemaster.ixion.org.uk, ixion at ixion.org.uk

... and various 'List' headers as follows:-

    List-Id: A group of bikers chatting down the pub <ixion.ixiemaster.ixion.org.uk>
    List-Post: <mailto:ixion at ixiemaster.ixion.org.uk>

When I L[ist Reply] the reply gets sent to both
ixion at ixiemaster.ixion.org.uk *and* ixion at ixion.org.uk.  Is there any
way I can configure mutt to send to only one of these?  (I can't just
always ignore one of them as sometimes only ixion at ixion.org.uk appears
as the list address).

-- 
Chris Green