No.
That rating is the capacity of a rechargeable battery, in this case 900mAh or milliamp hours. That battery should be able to put out 900milliamps for an hour or 450milliamps for two hours. Just because the battery is rated for 900mAh does not mean it will be able to put out a steady 900mA. Most rechargeables in my experiece do not push as much current as a standard alkaline battery.
AAA batteries are run in series in pen style hosts. They are run in series to double the voltage, but the maximum discharge rate is the same as both batteries. IE: two AAA batteries, each capable of a steady 400mA draw in series will give 3V at 400mA, no more. Rechargeable only run 1.2V so they will only run 400mA at 2.4V. A normal pen pointer will output less power on rechargeables (or not work at all) just because of the lower voltage.
Two AAAs in parallel would either double the capacity or double the maximum current draw. If you have the same two AAAs in parallel they will either provide 400mA at 1.5 volts twice as long or 800mA at 1.5v for the same period of time.
The fact remains, it's not happening. I honestly don't believe more than 125-150 of GREEN (no IR) is possible in a pen host. The OP and anyone buying the laser expecting more than 5mW is a gullible fool.