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The term "Hexatonic Triad Pairs" is actually a redundant phrase, or something known as a "pleonasm". It is, however, accurately self-descriptive and rolls off the tongue quite easily.
A true triad pair - which is formed from 2 adjacent triads and therefore comprised of 6 non repeating notes - always results in a hexatonic (6 note) scale. On the other hand, a hexatonic scale, being any scale of 6 notes, doesn't always yield a triad pair.