How are these AA batteries 4500 mAh?
Let's see- unknown brand name, claims of storage capacity beyond that of any remotely trustworthy manufacturer, found in a drawer so likely not engineering samples liberated from a top-secret skunkworks, and inability to spell the word "battery" on the label (BRTTERY?).

The whole thing screams arbitrarily labeled Asian-made product of the most dubious of origins. If you're lucky they'll function and have 2000mAh capacity for a few hundred charges.

If your computer thinks there is an alkaline AA cell in there it will report about half capacity since the NiMH cells have a lower voltage (1.2V vs 1.55V) when fully charged and a flatter discharge curve.

You could test the battery roughly by fully charging it and discharging it with a resistor but you'd have to monitor it to ensure the cell voltage did not drop below about 1V or the battery could be damaged. Make a measurement every 30 min or whatever and plot the result.