MPEG-TS Allows broadcasters to send multiple Video and Audio Streams over the same physical channel.
So, in DTV you can have channels like 6.1
Each maps to one Video PID, and one or more Audio PIDs
KVIE-DT 6.1 Video: 33, Audio: 36
KVIE-D2 6.2 Video: 49, Audio: 52
KVIE-D3 6.3 Video: 65, Audio: 68
KVIE-D4 6.4 Video: 81, Audio: 84
Actual broadcast channel: 53.
DTV Content is likely to be moved back to the stations original channels after the digital only cutover occurs.