Would two AA batteries in parallel do as much work as one D battery?

Both AA and D batteries are 1½ volts. A D battery is used where more current is required - it can deliver more power for longer.

For typical batteries with alkaline chemistry:

The typical capacity of a D battery is 12000 to 18000 mAh.

The typical capacity of an AA battery is 1200 to 2500 mAh.

Two AA batteries in parallel will supply twice their current rating, about 2400 to 5000 mAh. You would need 8 to 10 AA batteries in parallel to supply the current of a D battery.