The SWG output is 45 each (not sure what units those are - but I was told it’s the biggest capacity) and one of them is brand new as I only installed it last month when one wasn’t enough.
The Astral 45 unit will/should produce 45mg of Chlorine gas per hour when run at 100% drive level and with the appropriate level of salt in the water.
Testing that I have carried out in my pool shows that these cells tend to prefer the salt level to be up at around 4000ppm (as per manufacturer's recommendation). If your salt level drops to say 3000ppm then you will not be able to achieve full output.
BTW - How are the two cells connected - Via two independent chlorinators or some other method?