The two skeg method of steering was used by Don Currie (designer of the Dagger-board rudder) on his Nordkapp back in the late 1980s. Nothing new. The skegs were not in alignment with the keel so if one or other was dropped, it acted as a rudder to turn the kayak in a direction depending which blade was lowered. They were dropped using the rudder pedals and if you wanted to put the brakes on, I presume lowering both together would have done that.
It is obvious you don't lower either blade if the kayak is tracking in the direction you want it to.
The skegs were not in alignment with the keel.
sheesh . . . probably were in alignment w/ the sheer. Using that approach, one could do a released layup on the stern sheer down a few inches . . . . get a totally hidden BS rudder that way that gives more curvature the more it's deployed. [Don't anybody ever mention that I thought of that.]
Anyway, at least the two in the OP were aligned. . . well they do look a little wavy . . . maybe that's hydro-alumo-dynamics
I should have said "skegs" as in "skegs that were retracted on to the deck" or "non-steering rudders" as they were, when down, not in alignment with the keel so had a turning action. The deeper they were the greater the steering / turning action.