Postfix - Forward Mail To Multiple Destinations

Is there anyway to get postfix to forward email to multiple destinations? At work we use a redhat 9 box running postfix/amavis/spamassasin to filter out any spam or viruses before forwarding mail onto our exchange server. We are about to upgrade our exchange server from 5.5 to 2003 and temporarily want all our email to be delivered to both servers.
I see an old version of postfix allowed this by adding two destinations in the transport file, but current versions don't (I understand that the reason it worked on the old version was because of a bug).
Our ISP has one mx record for each of our domains to point to one of our public IPs. We have several other public IPs that are currently not being used. A secondary record allows email to be stored by the ISP if our mail server is unavailable. I've setup a static NAT on our firewall to deliver all email to our redhat spamfilter. I would rather the spamfilter handled the delivery to the two servers but would be interested to know if there are other ways to do this if postfix can't.

Thanks

A possibility might be something like procmail. Since postfix cant, simply feeding all mail through a filtering program like that can not only forward the mail, but also run it through your spam and anti-virus software. Downside is the nessicary reconfiguration.