RID and vorbisgain

i was messing around with replaygain (for preparation of the karma merge =) on my new ogg vorbis files, and it seems as if jemplode think that they're physically different than the original ones. i was under the impression that all the program did was write tags to the file. correct me if i'm wrong?

Oggs compute RID on the entire file vs MP3's that only compute on the data portion. This is due to artifacts of updating tags on oggs which require quite a bit of the oog file to change (from what I've heard).