I don't believe this behavior is "normal" for real aircraft and hope I don't develop bad reflex habits that carry over to my real flying.
You are correct, neither behavior (with or without springs) is normal for a real aircraft. Without springs would be closest to simulating a plane sitting still on the ground or during very low air speeds, and with springs is closest to simulating a plane at normal air speeds. To get the best of both worlds, you'd need force feedback, and as far as I know there are no 'consumer' grade rudder pedals like this. I'm sure there are commercial simulators out there that do simulate this, but I doubt anyone here could afford to purchase and install those to their PC, and even if they did I'm not sure Aces High even bothers to emulate a force feedback for the rudder surfaces anyway.
As far as carrying these 'bad habits' over to real aircraft... well I wouldn't worry so much about that. The human mind is an incredible thing and if it will know the difference. Just keep in mind that using rudder pedals (albeit with an unrealistic feel) is still more realistic than using the keyboard or a twisty stick for rudder, and that will transfer much more fluently to a real aircraft. What you're worried about would be like driving an M3 for twenty miles with the joystick on Aces High and then getting in your car and expecting your bad habits from driving with the joystick to interfere with your driving skills! It's just not going to happen. It's not like I accidentally try to steer with the floor shifter....