Quote:
I'm having trouble coming up with a parallel using different words, which is why I'm leaning towards colloquialism.

"Never, ever, assume"

"Quietly, so as not to wake the baby, he left the house"

Both commas are required, IMO. "Very, very quietly" is, as Bitt says, a different situation: two adverbs forming a comma-separated list, with only one comma required.

Peter