Most scanners are mono and most feeds are mono. Some feeds are set up like the KOAK - Oakland, CA feed. the left speaker is "Left Audio Channel: Oakland Tower: 127.2 Oakland Ground: 121.75 Oakland Clearance Delivery: 121.1". and the right speaker is "General Aviation (North Field) Right audio channel: Tower: 118.3 (Rwys 27L/R,9L/R,33/15) Oakland Ground: 121.9". You use the balance (Left and Right) on your media player to listen to one or both feeds at a time.
Oakland feed link http://alt.liveatc.net/koak