You need to check the other activities - chances
are one of those has an E command in the custom
buttons for either the TV or the receiver, and
that's being propogated to the Watch Local TV
activity. Or you're just overlooking it.

Cloning devices means adding multiple copies of
a device and using each copy of the device in
only one activity. So if you have a light controller
and 3 activities you'd add 3 light controller
devices that are identical and you'd add the first
one to the first activity, 2nd one to the 2nd
activity, 3rd one to the 3rd activity. Any custom
commands that are assigned won't be propogated
to the other activities because they don't have
the same light controller device.