If you can hear everything same is it was from inside bb on the export, I would not be concerned about this.


And, yes, some are indeed Mono while others are Stereo.

Drums are likely to always be Stereo tracks, many of the Pianos would be as well, that's how you properly Mic a piano.

There can be other reasons for differing file sizes of the tracks as well, for example, a track that is only invoked for a lesser amount of choruses can be shorter than a track that is there for he entire song length, or an instrument such as a horn is likely to be recorded as Mono, simply because there is nothing to gain from recording what is essentially a mono source, a horn with one bell, as a Stereo file.

If it sounds good, it IS good...


--Mac