I have WS-C3560E-12SD-E series switches with IOS (3560e-universalk9-mz.12.2.53.SE1) having two supplies (C3K-PWR-300WAC) installed. I noticed that only one power supply is showing in 'show env'. But i can see both the suplies in 'show inventory'. I checked the power supplies LED and all LEDs showing Green.
While i can see both power supplies in 'show env' & 'show inventory' on the same model (WS-C3560E-12SD-E) of switches running IOS 12.2.52.SE & 12.2.50.SE2