Early Disc Brake ?

Yes, 4 pist. KH.
Both sides freezing normal?

Yep. Par for the course. Rebuilt mine once when I first got the car 20 + years ago. I painstakingly unstuck all of the pistons, cleaned up everything only to have them seize up again a few years later. I had more money at that point, so I sent them off to have stainless sleeves & pistons installed.