If that was true, that the blades have the same angle at the retreating and advancing side, the helicopter would produce 2-3 times the lift on the advancing side at around 100 kn if the blades spin at around 400 kn tip speed. Not good for level flight.
What happens is that the blades starts producing more lift than it would be at a hover, as soon as it passes the 6 o'clock position on the rotor disk. This happens due to the increased velocity of the relative wind. Now an increase in lift makes the blade want to go up, and since helicoper blades can flap, the blade flaps up. This upward motion causes the relative wind to come from higher up, thereby reducing the AoA, and therefore also lift. The opposite happens at the retreating side. The higher the speed, the more the blades will flap to compensate. If this were not true, helicopters would not be able to accellerate out of a hover. And they would not be able to hover over a point on the ground in windy conditions. What i just explained is disymmetry of lift.
The aerodynamic hazard called retreating blade stall occurs when the forward speed of the helicopter is so great that the retreating blade has to flap so much that the AoA to the realtive wind exceed its critical angle of attack, and stalls, eliminating lift and dramatically increasing drag for the affected section of the rotordisk.