Local stations for all markets have 4-digit channel numbers, ie 8530 through 8546 in my market (Salt Lake City). With newer receivers, these channels will also be shown if you select their broadcast channel numbers (2 through 32 for me). The channels are not sent twice but the receiver redirects (maps) these channels from their 4-digit channel to their respective places so that you don't have to remember the 4-digit numbers for all of your local channels.
