Do Duracell AAA batteries have internal short circuit detection?
Alkaline batteries have an internal resistance. There isn't a current limiter as such, that's just the physical properties of alkaline chemistry and the limits of the relatively-small AAA battery.

The thermal vs. voltage effects you see relate to the the ionic properties of the battery, as it recovers from a high discharge. Multiple high discharges will deplete the battery faster than a continuous, moderate discharge.

More info here: http://data.energizer.com/pdfs/alkaline_appman.pdf

(Don't try that with a Li-ion, please.)