Yes.  Bouncing to mono.  I'll try switching the pan law and see how that goes.
 
I've just started using track lanes too.  Good to know about the Flatten Comp function!

Another option is to copy the audio from the two tracks to lanes of a new track, and use Bounce to Clips(s) to sum them.

brundlefly
Are you bouncing to a mono track? If you bounce mono tracks through a stereo bus to a mono track, you'll get a 3dB increase unless your pan law has a -3dB center. Normally you'd want to preserve whatever panning is on the tracks, so you'd bounce to stereo. But since you're just bouncing down a comp, I'm guessing there's no panning. In that case, try setting your pan law to use a -3dB center.
 
In the future, if you do our comping with the lanes of one track, you can bounce directly to a mono track without going through a stereo bus, and avoid the problem. Or use the Flatten Comp function to create the bounce as a new lane of the same track.
 

Hi. I'm having this same issue, bouncing a raw, mono voice-over track. Track source is mono, so in the master source, I'm choosing mono as well. Sure enough, the master is a stereo bus and the bounce is adding 3 db. What is a "pan law" and how do I adjust it? Thanks! 

I highly recommended choosing a Stereo track source when bouncing mono tracks. If you absolutely must have a mono track after bouncing, use the DSP Gain function to delete one of the channels, then choose Convert Stereo to Mono.

Anderton
I highly recommended choosing a Stereo track source when bouncing mono tracks. If you absolutely must have a mono track after bouncing, use the DSP Gain function to delete one of the channels, then choose Convert Stereo to Mono.

I highly recommended choosing a Stereo track source when bouncing mono tracks. [the source track IS a mono track. I'm trying to keep the file size in check on a narrated streaming video I'm doing. If I choose "stereo track source," does creating a stereo track from a mono track essentially double the size of the audio file?]