When BiaB loads a file, by default it checks to see if there is an audio file with the same name in the current directory. If there is, it will automatically load that into the audio track as well.

If you rendered the drum tracks by muting all the tracks except for the drums, that's probably how the track got created with the same name. Right clicking on the track, and they creating a .WAV file for only that track is probably the simplest thing to do if you only want a single track rendered.

Also, there's an option to turn that automatic behavior off, but I'm away from my computer right now, so can't look it up. But if you turn it off, BiaB will stop automatically loading the audio file, which is probably what you're after.

-- David Cuny
My virtual singer development blog

Vocal control, you say. Never heard of it. Is that some kind of ProTools thing?