No, you only have once instance of tvheadend - grep is finding two instances of 'tvheadend' in the output from 'ps' - one is the actual instance of tvheadend, the other is from the '| grep tvheadend'.
To avoid this use 'pgrep':
$ pgrep -a tvheadend
10805 /usr/bin/tvheadend -f -p /var/run/tvheadend.pid -u pi -g video
pgrep -a will show you the pid and the commandline, pgrep on its own will just show you the pid.
Now to your problem - you appear to have TVH installed & running.
Can I give you a little bit of advice? When asking for technical help, it's far, far more useful to document than to decribe - e.g. "I've attempted to 'stop' and 'restart' tvheadend with -C and/or --noacl (as recommended in FAQ #2) to no avail." Tells me you've tried something [good], but doesn't tell me exactly how you've done that - and details can be important.
Relaying the exact commands you've entered, and their output will give me [and anyone else reading] a lot more to go on.
BTW, w.r.t "Superuser ID and password do not work." Are you referring to a TVH superuser name entered during installation, or something else? [TVH doesn't know your system superuser details].
