Expired cache files aren't deleted for domain aliases

Hi,

I have a pretty frustrating problem with purging expired cache files on my website. I have two domains that are showing the same content -> maindomain.com and domainalias.com

I noticed that in my cache directory there are 4 subdirectories: "www.maindomain.com", "maindomain.com", "www.domainalias.com" and "domainalias.com"

If I'm logged in at www.maindomain.com and I publish/change/delete an node on the frontpage, cached frontpage (and the added/modified/deleted node) in /cache/normal/www.maindomain.com/ is purged as it should, but the frontpage (and the node itself) on maindomain.com, domainalias.com and www.domainalias.com is still showing the old cached page, i.e. the cached files in those other cache subdirectories haven't been purged as they should've been. After the next cron run (if the files have reached their maximum life time) they are deleted and then everything is OK.

Why when I add/update/delete nodes their cached files in all directories ("www.maindomain.com", "maindomain.com", "www.domainalias.com" and "domainalias.com") aren't deleted?

I have turned on the following options in Boost settings:

+ Clear expired pages on cron runs
+ Clear the front page cache when promoted
+ Clear all cached pages referenced via CCK with a node on insert/update/delete
+ Clear all cached terms pages associated with a node on insert/update/delete
+ Clear all cached views pages associated with a node on update/delete
+ Clear all cached views pages associated with a node on insert
+ Flush all sites caches in this database (singe db, multisite)

Am I missing something or is this a bug in the Boost module?