I stand corrected, the definitions sections define a "Treble Hook" (singular) as a hook (again singular) with 3 points on a common shank. So by this definition it seems legal not just to have a treble, but in fact TWO trebles on your pipe jig if you want.

They do appear to need to be entirely barbless however.
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The charm of fishing is that it is the pursuit of what is elusive but attainable, a perpetual series of occasions for hope. -John Buchan