Question about A320 Pneumatic System operation

[AzmirAhmmhed]

I know that when APU bleed is on, the X-Bleed valve is open and the Engine 1+2 Bleed valves are closed. My question is if the X-Bleed valve stays open during engine start (as I think it does, https://showbox.bio/ https://tutuapp.uno/ https://vidmate.cool/ it only closes when APU bleed is off to my knowledge), does that mean that APU Bleed pressure is present in the left and right system, does that mean that both engines can potentially be started at once? If not, how is the air pressure directed only to the starting engine (which is usually 2)?

[oskaulata]

Bleed air is extracted from the compressor of the engine or APU. The specific stage of the compressor from which the air is bled varies by engine type. In some engines, air may be taken from more than one location for different uses as the temperature and pressure of the air is variable dependant cinema hd v2 upon the compressor stage at which it is extracted. Bleed air typically has a temperature of 200 – 250 degrees C. and a pressure of approximately 40 PSI exiting the engine pylon.
Bleed air, extracted from either the Auxiliary Power Unit (APU) or another operating engine is used to power an air turbine starter motor to start the engine. The primary advantage of an air turbine starter is that a given amount of torque can be produced by a smaller and lighter unit than would be the case if it was electrically or hydraulically powered.