Four months ago, I had a seized brake in the front left. The slide bearing was stuck and the outer pad was worn more than the inner (at the piston). I wasn't able to move the journals of the bearing by hand and used a tool to get it moving again. Since cleaning the bearings didn't help, I removed any rust / oxidation from the holes with sandpaper, cleaned them, and assembled new journals with lots of that special grease shipped with them.
However, the problem is back again, and I'm thinking about replacing the entire caliper to get rid of the problem.
Should calipers be replaced on both sides, though there's just a problem on one side, as it's done for tires, pads and rotors?
EDIT: Car is a small Kia Picanto (BA) 2008, just made 100,000km
The calipers seem to be a single, solid part, without exchangeable bearings (the "hole"). As said, I already changed the journals (the movable part inside the hole) with temporary success, the brake is now running hot again. Hardly noticeable at low speed, but at 130-140km/h, I sometimes can hear that noise of a hot / worn brake again and the brake is significantly hotter than the one on the other wheel after that. (Also strange: sometimes, the noise is there at 120km/h, sometimes at 140km/h, sometimes, there is none)
Finally, I don't want to mess with new journals again, and have the same problem in some months. The brake got really hot last time, and I would like to replace it. I can get it for 100€, which is not so much compared to 17€ for new journals.