Taking 2 audio channels and exporting them to 1 Channel with a left and right in Premiere Pro

HI!

I was hoping to find someone who can help me figure out a sequence setting/ export setting that would enable me to export 2 audio channels (1 track, 1 nat/music) into 1 channel that has a left and a right that mimics 1 track, 1 nat/sound.  Ive seen it done before, so I know its possible.  Help!