You are seeing the secondary channel because you have 40Mhz or 20/40 Auto bandwidth selected.
If you are connecting devices that can utilized the 40Mhz bandwidth (802.11n) then you should leave it
enabled on your router. If all your devices are only 802.11g, you can change to the router to 20Mhz only to reduce interference. Try to stick with channels 1,6, or 11. If you can talk to your neighbors to coordinate, that will help everyone out if they also stick with this channel plan, as it eliminates the overlaps. Everybody wins !
Choices for band selection when you have overlap with neighbors that you can't resolve:
1) Pick a band that doesn't overlap or has minimal overlap (3 or 4 channel seperation).
2) Pick exactly the SAME channel as your neighbor. If you are using this choice, you probably see multiple conflicts. Pick the weakest conflicting signal to match channels with (hopefully at least 20db signal strength seperation. This choice forces negotiation, but is better than collisions.
3) Overlap the weakest conflicting signal. You need to have at least 20db difference in signal strength. Generally you are better off with option 2... but YMMV.