DAQ should fail to start if there are duplicate channel names.

LLO recently had an issue where duplicate channels were inadvertently added to the EDC channel list. After a power outage forced a DAQ restart, these duplicate channels started getting written by the framewriter into the raw, second trend, and minute trend frames. framecpp_verify reported this as an error on the LDAS side.

Duplicate channel names are prohibited by the frame specification. The DAQ should fail to start if it finds duplicate channel names, and the framewriter should fail to write frames if duplicates exist.