How do I calculate if two power adapters will output the same energy if they have different voltages?
In general it is acceptable to use an adapter that can provide more current than the device needs - the device will only use what it needs.

The voltage must be correct though.

In your example a 12V 1Amp or 2Amp adapter would be OK.

Make sure that the supply is AC or DC as shown on the device.

If DC make sure that the polarity is correct.

If you don't get these things correct the device may be destroyed.