I was looking at writing a program to duplicate specific XML channel data and repeating the data but under a different Channel name.
I would be surprised if you couldn't find an application already written to do that.
I know the
EPG Collector can do it. Using the Timeshift tab in its setup, with a time shift of zero, EPGC just copies the XMLTV from one channel to another, using the same times. If you add a time shift, it copies the data over with an adjustment to the program start and end times, as appropriate.
For example, in the first image below, you can see the I have three "7 Digital" channels, two called "7 Digital" and one called "7 Digital 1", channels 7, 70, and 71. They all show the same content on different transport streams. Only the first channel has any EPG data associated with it. Using the EPGC capabilities I can copy that EPG data to the other two channels, as per the first image.
As EPGC can also import externally sourced EPG data into the data it collects, and merge the two, giving preference to one source or the other, it should be easy to import the XmltvGUI data, copy it to the other channel, then import into MC.
It certainly doesn't matter if you are happy to always record the HD channel, but if you want the option of recording smaller files using the SD channel, EPGC is one way you could populate the EPG data for the SD channel.