[Relativity]

if you setup a primary and secondary zip code in the Off-Air Channels setup, and both markets have the same channel (for example, 4-1) then you'll find that both channels will appear in your guide and you can't remove one of them (the secondary one)

If you go to the Edit Off-Air Channel List, you'll find the secondary duplicate channel doesn't exist. Example: 4-1 (WCBS primary market) and 4-1 (WNBC secondary market)

when you go to your guide, both channels will appear.

The only way to remove the channel is to use favorites

 

[gcd0865]

I believe this is a bug of the AM21, where artifacts of stations remain in the populated OTA channel listing, with discrepancies between the on-screen guide and the separate OTA listing.

Re-run the full OTA setup 2 or 3 times, including full resets/"initial setups" that clear all channels. Eventually, the AM21 will get the listings right, and will be consistent between the on-screen guide and the OTA channel listing. Others (including me) have reported this problem with the AM21.

 

[texasbrit]

Yes, it's a bug, but difficult to get around. But if the FCC had made the stations use their real channel number, instead of this "virtual" channel allocation, it would not have been a problem. Creates chaos where you have repeaters using the same virtual channel number as the original source channel, in a location that gets both of them.
Similar problem with most TVs, by the way; if you have two 4-1s in the channel list, and you key in 4-1, which channel do you think you should get?

I think if you delete the "primary" zip code, so you only have the stations from the secondary one, including the station you want to delete; then delete it, then add in the primary zip code, you will get what you need.