Hi bigmuscles,
Thanks for trying Media Center and welcome to Interact.
Currently DVB-T and DVB-S channels can not be merged. You need to keep both set of channels. Although this makes your channel list a little cluttered, it does not affect your ability to record one channel while watching another. When you schedule to record, try using DVB-T for those overlapped channels so you can free up DVB-S tuner for other channels that are only available on DVB-S.
You can watch a channel while it is being recorded. This way you will not use two tuners for the same program.