iPhoto 08 has got something wrong with the web gallery (publish to gallery.me.com). If you rapidly drag over a handful of photos to an existing web gallery, you start to see multiples of random photos in the web gallery. However, as it's published, it seems these multiples do not appear.
The problem is that deleting them from the iPhoto web album is not guaranteed to remove it; I'm wondering if it's a cached thumbnail problem?