I think Triathlon folks are the niche market for those so may be short pull capacity . as they run road bikes
and those short reach short pull calipers.
2 levers > one brake .... brifters + on aero bar ends, reverse levers..

I run trekking bars , for steep descents , I'm on the back of the bars where the brake levers are..

and push my backside off the back of the saddle to lower my C-of-G.. to prevent endos.


BTW there are brake levers which pull 2 cables simultaneously too ..

& Magura's Hydro rim brakes can daisy chain 2 levers on the master end,
just like they use 2 calipers on the slave end, 1 mounted on each V brake post.

Closed system, just mineral oil after all the air is bled out.