Whether (revisited)

Didn't mean to revive the discussion of "whether" so soon, but I just now heard a sportscaster announce, ". . . he doesn't know whether or not he will . . . or not . . .." Whoa, Nelly. All you need is one "whether." "I don't know whether I'll be able to visit you tomorrow." That's clear as a bell, right? (Ok, I usually avoid cliches like the plague.) No need to throw in "whether or not." The best example I ever heard of what not to say in this context was by a newscaster following a tornado in my area. She reported something to the effect of, "We don't know now whether or not he is living or whether or not he is dead." Sorry for the disastrous reference, but grammatically that line is the literal epitome of overkill!